article by Lisa
February 17, 2026
"A pro baker's guide to strawberry rhubarb crisp bars: buttery oat crust, tart-sweet filling and a crunchy crumble. Tips, variations and baking techniques."
Introduction — Summer in every bite
Bright, tangy, and irresistibly crunchy
As a professional recipe creator I always chase that balance where texture and flavor do the talking: a buttery, slightly gritty oat base that gives way to a vibrant, tart-sweet filling, finished with a coarse, golden crumble. This recipe captures that summer moment in handheld form — convenient for picnics, beautiful for bake sales, and deeply comforting sliced warm with a scoop of ice cream beside it.
What you'll notice first
The first bite should offer contrast: a crisp, slightly firm crust; a juicy, lively filling with a glossy sheen; and a topping that crackles under your teeth. I care about how the oat bits remain assertive after baking rather than dissolve into dust. That integrity in texture is what transforms simple pantry ingredients into something that feels artisanal.
Tone and approach
Throughout this article I’ll treat each technical choice like a deliberate brushstroke — why cold butter matters for pockets of flake, how the fruit’s natural juices behave, and which visual cues tell you the bars are done. Expect practical tips, sensory checkpoints, and a handful of creative swaps so you can adapt this foundation to your summer harvest or local market finds.
As a professional recipe creator I always chase that balance where texture and flavor do the talking: a buttery, slightly gritty oat base that gives way to a vibrant, tart-sweet filling, finished with a coarse, golden crumble. This recipe captures that summer moment in handheld form — convenient for picnics, beautiful for bake sales, and deeply comforting sliced warm with a scoop of ice cream beside it.
What you'll notice first
The first bite should offer contrast: a crisp, slightly firm crust; a juicy, lively filling with a glossy sheen; and a topping that crackles under your teeth. I care about how the oat bits remain assertive after baking rather than dissolve into dust. That integrity in texture is what transforms simple pantry ingredients into something that feels artisanal.
Tone and approach
Throughout this article I’ll treat each technical choice like a deliberate brushstroke — why cold butter matters for pockets of flake, how the fruit’s natural juices behave, and which visual cues tell you the bars are done. Expect practical tips, sensory checkpoints, and a handful of creative swaps so you can adapt this foundation to your summer harvest or local market finds.
Gathering Ingredients
Full ingredient list
Selecting produce and pantry items
Choose strawberries that smell fragrant and are uniformly red; they’ll add sweetness and perfume without needing heavy sugar. For rhubarb, look for firm, crisp stalks with bright color — avoid limp or overly fibrous pieces. In the pantry, old-fashioned rolled oats give the topping its best texture: they hold shape and toast beautifully. If you prefer a gluten-free build, use a certified gluten-free oat and a 1:1 gluten-free flour blend in the crust.
Butter and temperature
Cold butter is non-negotiable if you want signature flakiness and small, buttery pockets in the crumb; cubing and keeping it chilled until the last moment preserves that. For the sugars, a combination of granulated and light brown gives a rounded sweetness with a whisper of molasses from the brown sugar that enhances the fruit without overpowering it.
Storage and prepping ahead
You can prep dry crumble mix in advance and keep it chilled; fruits are best macerated shortly before assembly to retain brightness. If you must stash chopped rhubarb, keep it wrapped and very cold to prevent flavor loss. These small prep choices pay dividends in the final texture and clarity of fruit flavor.
- 2 cups fresh strawberries, hulled and quartered
- 3 cups chopped rhubarb (about 4–5 stalks)
- 3/4 cup granulated sugar
- 1/4 cup light brown sugar
- 2 tbsp cornstarch (or arrowroot)
- 1 tbsp lemon juice
- 1 tsp vanilla extract
- 1 1/2 cups all-purpose flour
- 1 1/2 cups old-fashioned rolled oats
- 3/4 cup cold unsalted butter, cubed
- 1/2 tsp salt
- 1 tsp ground cinnamon (optional)
- 1/2 tsp baking powder
Selecting produce and pantry items
Choose strawberries that smell fragrant and are uniformly red; they’ll add sweetness and perfume without needing heavy sugar. For rhubarb, look for firm, crisp stalks with bright color — avoid limp or overly fibrous pieces. In the pantry, old-fashioned rolled oats give the topping its best texture: they hold shape and toast beautifully. If you prefer a gluten-free build, use a certified gluten-free oat and a 1:1 gluten-free flour blend in the crust.
Butter and temperature
Cold butter is non-negotiable if you want signature flakiness and small, buttery pockets in the crumb; cubing and keeping it chilled until the last moment preserves that. For the sugars, a combination of granulated and light brown gives a rounded sweetness with a whisper of molasses from the brown sugar that enhances the fruit without overpowering it.
Storage and prepping ahead
You can prep dry crumble mix in advance and keep it chilled; fruits are best macerated shortly before assembly to retain brightness. If you must stash chopped rhubarb, keep it wrapped and very cold to prevent flavor loss. These small prep choices pay dividends in the final texture and clarity of fruit flavor.
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Equipment and mise en place
Right tools, minimal fuss
The equipment choices you make simplify assembly and control outcomes. A 9x9-inch square pan gives an ideal depth-to-surface ratio for these bars; a rimmed pan ensures juices can bubble without overflowing. Lining with parchment that creates an overhang is the small, professional touch that makes unmolding effortless and keeps edges pristine.
Hand tools that matter
Why these choices work
The pastry cutter helps keep pea-sized butter bits for textural pockets; if you overwork the butter the mixture can turn pasty and lose its structural contrast. A bench scraper or flat-bottomed measuring cup is the quickest way to press the base evenly and compactly without compressing out all the air — that compactness supports a clean cut after cooling. Finally, a wire rack lets air circulate underneath so the filling sets without steaming the crust from below, preserving crunch.
The equipment choices you make simplify assembly and control outcomes. A 9x9-inch square pan gives an ideal depth-to-surface ratio for these bars; a rimmed pan ensures juices can bubble without overflowing. Lining with parchment that creates an overhang is the small, professional touch that makes unmolding effortless and keeps edges pristine.
Hand tools that matter
- A pastry cutter or two forks (or your fingertips) for coating cold butter into the dry mix
- A medium bowl for macerating fruit
- A sturdy spatula or bench scraper for pressing the crust
- A wire rack for cooling
Why these choices work
The pastry cutter helps keep pea-sized butter bits for textural pockets; if you overwork the butter the mixture can turn pasty and lose its structural contrast. A bench scraper or flat-bottomed measuring cup is the quickest way to press the base evenly and compactly without compressing out all the air — that compactness supports a clean cut after cooling. Finally, a wire rack lets air circulate underneath so the filling sets without steaming the crust from below, preserving crunch.
Crust and crumble technique
Textural intent for crust and topping
The crust should be supportive but tender — a delicate balance between structure and bite. The topping needs to be coarse enough to offer crunchy contrast after baking rather than collapsing into powder. Hitting those textures comes down to fat temperature, mixing method, and how you distribute the reserved crumbs.
Butter handling
Use cold butter cut into cubes and work it into the dry mix just until you see coarse crumbs with some pea-sized pieces remaining; those pea-sized bits are what brown into buttery pockets. If you like a slightly finer crumble, work a touch more, but beware of melting the butter in your palms — the heat there is deceptively effective at changing the mixture’s behavior.
Pressing and distributing
Press the bulk of the mixture firmly into the pan to form the base; the act of pressing compacts the dough and creates a cohesive platform for the filling. For the topping, scatter the reserved mixture broadly and allow overlaps; as it bakes the uneven surface produces those caramelized nooks that give each bite a variety of textures.
Optional finishing touches
For an extra visual and textural lift, toss a small handful of larger oat flakes into the reserved crumble. They will toast on the surface and provide attractive rustic peaks.
The crust should be supportive but tender — a delicate balance between structure and bite. The topping needs to be coarse enough to offer crunchy contrast after baking rather than collapsing into powder. Hitting those textures comes down to fat temperature, mixing method, and how you distribute the reserved crumbs.
Butter handling
Use cold butter cut into cubes and work it into the dry mix just until you see coarse crumbs with some pea-sized pieces remaining; those pea-sized bits are what brown into buttery pockets. If you like a slightly finer crumble, work a touch more, but beware of melting the butter in your palms — the heat there is deceptively effective at changing the mixture’s behavior.
Pressing and distributing
Press the bulk of the mixture firmly into the pan to form the base; the act of pressing compacts the dough and creates a cohesive platform for the filling. For the topping, scatter the reserved mixture broadly and allow overlaps; as it bakes the uneven surface produces those caramelized nooks that give each bite a variety of textures.
Optional finishing touches
For an extra visual and textural lift, toss a small handful of larger oat flakes into the reserved crumble. They will toast on the surface and provide attractive rustic peaks.
Filling: flavor balance and texture
The role of each element
The fruit provides bright acidity and juice; the sugar tames harshness and amplifies fruit aromatics; the starch binds the liquid while preserving body and gloss. The goal is a filling that’s glossy and perky, not runny puddle or dry compote — it should hold together when you slice bars but still exude a little syrupy sheen.
Handling the fruit
Macerating briefly extracts juices and smooths the flavor, but over-maceration can cause the fruit to lose vibrant texture. Gentle stirring and a short rest lets the pieces marry with sugar and aromatics. Because strawberries are tender and rhubarb is crisper and more fibrous, the combination yields a pleasing duality of mouthfeel that I always favor.
Starch choices and thickening
Cornstarch (or arrowroot) is a neutral thickener that clears to a glossy finish. It’s important to mix it evenly with the sugar before adding to the fruit so it disperses and activates uniformly during baking. The perfect thickening gives you visible, syrupy pockets between fruit chunks rather than a slurry.
Aromatics and brightness
A splash of citrus and a hint of vanilla lift the fruit into something more complex. Preserve brightness by avoiding heavy-handed spices — a touch of cinnamon can whisper warmth but shouldn’t mask the fruit’s natural vibrancy.
The fruit provides bright acidity and juice; the sugar tames harshness and amplifies fruit aromatics; the starch binds the liquid while preserving body and gloss. The goal is a filling that’s glossy and perky, not runny puddle or dry compote — it should hold together when you slice bars but still exude a little syrupy sheen.
Handling the fruit
Macerating briefly extracts juices and smooths the flavor, but over-maceration can cause the fruit to lose vibrant texture. Gentle stirring and a short rest lets the pieces marry with sugar and aromatics. Because strawberries are tender and rhubarb is crisper and more fibrous, the combination yields a pleasing duality of mouthfeel that I always favor.
Starch choices and thickening
Cornstarch (or arrowroot) is a neutral thickener that clears to a glossy finish. It’s important to mix it evenly with the sugar before adding to the fruit so it disperses and activates uniformly during baking. The perfect thickening gives you visible, syrupy pockets between fruit chunks rather than a slurry.
Aromatics and brightness
A splash of citrus and a hint of vanilla lift the fruit into something more complex. Preserve brightness by avoiding heavy-handed spices — a touch of cinnamon can whisper warmth but shouldn’t mask the fruit’s natural vibrancy.
Step-by-step Instructions
Method laid out clearly
A note on timing and visuals
Follow the listed baking cues closely and rely on visual checkpoints — bubbling at the edges and a golden top — to judge doneness. The final cooling period is essential for clean slices, so resist the urge to cut while still warm unless you prefer a rustic, slightly oozing presentation.
- Preheat the oven to 375°F (190°C). Line a 9x9-inch (23x23 cm) baking pan with parchment, leaving an overhang for easy removal.
- In a medium bowl, toss the strawberries and rhubarb with the granulated sugar, cornstarch, lemon juice and vanilla until evenly coated. Set aside to macerate while you make the crust.
- In a large bowl, whisk together the flour, rolled oats, brown sugar, salt, cinnamon and baking powder.
- Cut the cold butter into the dry mixture using a pastry cutter, two forks, or your fingertips until the mixture resembles coarse crumbs with some pea-sized bits.
- Reserve about 1 1/2 cups of the oat-crumble mixture for the topping. Press the remaining mixture firmly and evenly into the bottom of the prepared pan to form the crust.
- Spread the strawberry‑rhubarb filling evenly over the crust, making sure juices are distributed.
- Sprinkle the reserved oat crumble over the fruit layer, covering as much as possible.
- Bake for 35–45 minutes, until the top is golden and the filling is bubbling at the edges. If the topping browns too quickly, tent loosely with foil for the last 10 minutes.
- Remove from the oven and let cool completely in the pan on a wire rack (this helps the filling set). Once cool, lift out with the parchment overhang and cut into bars.
- Serve at room temperature or slightly chilled. Store in an airtight container in the refrigerator for up to 4 days, or freeze individually wrapped for longer.
A note on timing and visuals
Follow the listed baking cues closely and rely on visual checkpoints — bubbling at the edges and a golden top — to judge doneness. The final cooling period is essential for clean slices, so resist the urge to cut while still warm unless you prefer a rustic, slightly oozing presentation.
Cooking Process
Reading the bake as it happens
Watching the bars transform in the oven is where technique matters most. Early on you’ll notice steam rising and the fruit releasing juices; as the bake progresses, the topping will transition from pale and matte to bronzed and textured. Those changes tell you about caramelization, moisture migration, and when the filling is interacting properly with the thickener.
Visual and tactile cues
Look for the filling to bubble visibly at the edges — that bubbling confirms the starch has gelatinized and the liquid is thickening. The topping should be an even golden brown with a few darker bronzed spots; if you see aggressive darkening before the filling bubbles, tent loosely with foil to slow surface browning while the interior finishes.
Handling during the bake
Open the oven only once or twice to check, using an oven mitt and keeping the door open briefly to avoid major temperature swings. If juices are running too freely and the topping is still pale, a gentle nudge of higher heat for the last moments will encourage caramelization without burning — but this is a calculated move that benefits from attentive monitoring.
Serving straight from the oven
If you enjoy warm bars, let them cool enough to be safe to handle but still tender — the filling will be slightly more fluid when warm, offering a luscious mouthfeel. For cleaner slices, allow the entire pan to cool fully so the filling sets into a defined layer; this resting period sharpens textures and makes each bar easier to transport.
Watching the bars transform in the oven is where technique matters most. Early on you’ll notice steam rising and the fruit releasing juices; as the bake progresses, the topping will transition from pale and matte to bronzed and textured. Those changes tell you about caramelization, moisture migration, and when the filling is interacting properly with the thickener.
Visual and tactile cues
Look for the filling to bubble visibly at the edges — that bubbling confirms the starch has gelatinized and the liquid is thickening. The topping should be an even golden brown with a few darker bronzed spots; if you see aggressive darkening before the filling bubbles, tent loosely with foil to slow surface browning while the interior finishes.
Handling during the bake
Open the oven only once or twice to check, using an oven mitt and keeping the door open briefly to avoid major temperature swings. If juices are running too freely and the topping is still pale, a gentle nudge of higher heat for the last moments will encourage caramelization without burning — but this is a calculated move that benefits from attentive monitoring.
Serving straight from the oven
If you enjoy warm bars, let them cool enough to be safe to handle but still tender — the filling will be slightly more fluid when warm, offering a luscious mouthfeel. For cleaner slices, allow the entire pan to cool fully so the filling sets into a defined layer; this resting period sharpens textures and makes each bar easier to transport.
Cooling, serving and storage
Why cooling matters
Cooling is a finishing technique that determines structure as much as anything you do before bake. As the pan returns to room temperature the filling’s starches and pectin firm up, juices set into glossy pockets, and the bar holds a neat profile when sliced. Removing bars too soon yields a more rustic, slightly molten texture; allowing them to set yields cleaner layers and easier transport.
Serving ideas
These bars are versatile: enjoy them as-is for a picnic-friendly option, slightly chilled for tidy slices, or warm with an accompaniment that contrasts textures and temperatures. A neutral, lightly set cream or a scoop of vanilla ice cream pairs well because it complements the fruit without competing with the oat crunch.
Storing like a pro
Store bars in an airtight container layered with parchment to prevent sticking. Refrigeration extends freshness and preserves filling integrity; individual freezing is a great method for long-term storage and makes grabbing a single portion hassle-free. When thawing frozen bars, bring them back to room temperature for the most balanced texture or warm briefly if you prefer them soft.
Transport tips
For picnics, arrange bars in a single layer or separate layers with parchment. If you need to move them warm, set them on a flat, heat-stable surface to cool slightly before packing; this minimizes steam condensation that can soften the topping.
Cooling is a finishing technique that determines structure as much as anything you do before bake. As the pan returns to room temperature the filling’s starches and pectin firm up, juices set into glossy pockets, and the bar holds a neat profile when sliced. Removing bars too soon yields a more rustic, slightly molten texture; allowing them to set yields cleaner layers and easier transport.
Serving ideas
These bars are versatile: enjoy them as-is for a picnic-friendly option, slightly chilled for tidy slices, or warm with an accompaniment that contrasts textures and temperatures. A neutral, lightly set cream or a scoop of vanilla ice cream pairs well because it complements the fruit without competing with the oat crunch.
Storing like a pro
Store bars in an airtight container layered with parchment to prevent sticking. Refrigeration extends freshness and preserves filling integrity; individual freezing is a great method for long-term storage and makes grabbing a single portion hassle-free. When thawing frozen bars, bring them back to room temperature for the most balanced texture or warm briefly if you prefer them soft.
Transport tips
For picnics, arrange bars in a single layer or separate layers with parchment. If you need to move them warm, set them on a flat, heat-stable surface to cool slightly before packing; this minimizes steam condensation that can soften the topping.
Variations, swaps and seasonal ideas
Fruit variations
The bar formula — structured oat base, juicy fruit layer, and coarse crumble — is wonderfully adaptable. Swap strawberries for raspberries or add diced apples for a less tart profile. If you have abundant stone fruit, halves or slices can work if cut to similar size as the original fruits so the bake is even.
Texture and dietary swaps
To make the bars gluten-free, select certified gluten-free oats and a 1:1 gluten-free flour blend for the base. For a nutty depth, fold a small handful of toasted chopped nuts into the topping, or replace part of the butter with coconut oil for a subtly tropical aroma — note that alternative fats can change the crumble behavior and toasting point.
Flavor lifts
A little citrus zest folded into the filling can add perfume without increasing acidity, and a dash of ground cardamom or ginger can shift the profile toward warm, aromatic territory. Be judicious: these bars succeed when the fruit remains the star.
Presentation variations
Cutting into smaller squares suits bite-sized servings, while larger rectangles feel more rustic and substantial. For gifting, wrap stacks in parchment and tie with twine; a label noting the primary fruits adds charm and clarity.
The bar formula — structured oat base, juicy fruit layer, and coarse crumble — is wonderfully adaptable. Swap strawberries for raspberries or add diced apples for a less tart profile. If you have abundant stone fruit, halves or slices can work if cut to similar size as the original fruits so the bake is even.
Texture and dietary swaps
To make the bars gluten-free, select certified gluten-free oats and a 1:1 gluten-free flour blend for the base. For a nutty depth, fold a small handful of toasted chopped nuts into the topping, or replace part of the butter with coconut oil for a subtly tropical aroma — note that alternative fats can change the crumble behavior and toasting point.
Flavor lifts
A little citrus zest folded into the filling can add perfume without increasing acidity, and a dash of ground cardamom or ginger can shift the profile toward warm, aromatic territory. Be judicious: these bars succeed when the fruit remains the star.
Presentation variations
Cutting into smaller squares suits bite-sized servings, while larger rectangles feel more rustic and substantial. For gifting, wrap stacks in parchment and tie with twine; a label noting the primary fruits adds charm and clarity.
Troubleshooting and pro tips
Soggy bottom? Look at heat and drainage
If the crust seems underbaked or soggy, it’s often due to excess liquid from fruit or insufficient compaction of the base. Compacting the crust firmly helps it resist moisture penetration; using a drier fruit mix (or briefly macerating and draining surplus liquid) can also keep the base crisp.
Topping browns too fast
If the surface is bronzing before the filling sets, tent loosely with foil to shield direct heat while allowing the interior to finish. This gives you caramelization control without sacrificing internal doneness.
Filling too runny
Runny filling can come from under-thickening or fruit that releases excessive juice. Ensure the starch is well distributed and activated; if you face consistently runny results with very juicy fruit, consider increasing the starch slightly or reducing the fruit’s free liquid before assembly.
Crumb too dense
Overworking the butter into the dry mix can yield a pastier texture rather than a crisp crumble. Aim for a mixture with a range of particle sizes — from fine grit to pea-sized pieces — so it bakes with layered crunch.
Slicing tips
For neat edges, chill fully and use a sharp knife wiped clean between cuts. A warm knife will smear; a cold, dry blade slices cleanly through set filling and crumbs.
If the crust seems underbaked or soggy, it’s often due to excess liquid from fruit or insufficient compaction of the base. Compacting the crust firmly helps it resist moisture penetration; using a drier fruit mix (or briefly macerating and draining surplus liquid) can also keep the base crisp.
Topping browns too fast
If the surface is bronzing before the filling sets, tent loosely with foil to shield direct heat while allowing the interior to finish. This gives you caramelization control without sacrificing internal doneness.
Filling too runny
Runny filling can come from under-thickening or fruit that releases excessive juice. Ensure the starch is well distributed and activated; if you face consistently runny results with very juicy fruit, consider increasing the starch slightly or reducing the fruit’s free liquid before assembly.
Crumb too dense
Overworking the butter into the dry mix can yield a pastier texture rather than a crisp crumble. Aim for a mixture with a range of particle sizes — from fine grit to pea-sized pieces — so it bakes with layered crunch.
Slicing tips
For neat edges, chill fully and use a sharp knife wiped clean between cuts. A warm knife will smear; a cold, dry blade slices cleanly through set filling and crumbs.
FAQs — Frequently asked questions
Can I use frozen fruit?
Yes, but frozen fruit releases more liquid as it thaws. If using frozen strawberries or rhubarb, thaw and drain excess liquid, then toss quickly with the thickener right before assembling to avoid a watery filling.
How do I know when the filling is set?
Watch for visible bubbling at the edges and a glossy, slightly thickened surface; these are better cues than color alone. The filling gains structure as it cools, so brief resting after baking always helps.
Can I make the crumble topping ahead?
Yes — the dry crumble mixture can be mixed and refrigerated for several days. Keep the butter cold and incorporate it just before assembling to preserve those desirable pea-sized pockets.
How should I reheat bars?
Warm them briefly in a low oven for a fresh-from-the-bakery feeling, or microwave for a few seconds for a quick, warm bite. If frozen, thaw in the refrigerator before reheating for the best texture.
Can I reduce sugar?
You can reduce sugar modestly, but it will affect both sweetness and how the filling gels and browns. If you prefer less sweet bars, consider cutting granulated sugar slightly and allowing fully ripe fruit to contribute natural sweetness instead.
Yes, but frozen fruit releases more liquid as it thaws. If using frozen strawberries or rhubarb, thaw and drain excess liquid, then toss quickly with the thickener right before assembling to avoid a watery filling.
How do I know when the filling is set?
Watch for visible bubbling at the edges and a glossy, slightly thickened surface; these are better cues than color alone. The filling gains structure as it cools, so brief resting after baking always helps.
Can I make the crumble topping ahead?
Yes — the dry crumble mixture can be mixed and refrigerated for several days. Keep the butter cold and incorporate it just before assembling to preserve those desirable pea-sized pockets.
How should I reheat bars?
Warm them briefly in a low oven for a fresh-from-the-bakery feeling, or microwave for a few seconds for a quick, warm bite. If frozen, thaw in the refrigerator before reheating for the best texture.
Can I reduce sugar?
You can reduce sugar modestly, but it will affect both sweetness and how the filling gels and browns. If you prefer less sweet bars, consider cutting granulated sugar slightly and allowing fully ripe fruit to contribute natural sweetness instead.
Strawberry Rhubarb Crisp Bars
Bright, tangy and irresistibly crunchy: Strawberry Rhubarb Crisp Bars are summer in a bite! Buttery oat crust, sweet-tart strawberry‑rhubarb filling and a crisp crumble topping — perfect for picnics or a cozy dessert. 🍓🥬🧈
total time
60
servings
9
calories
320 kcal
ingredients
- 2 cups fresh strawberries, hulled and quartered 🍓
- 3 cups chopped rhubarb (about 4–5 stalks) 🥬
- 3/4 cup granulated sugar 🍚
- 1/4 cup light brown sugar 🍯
- 2 tbsp cornstarch (or arrowroot) 🌽
- 1 tbsp lemon juice 🍋
- 1 tsp vanilla extract 🌿
- 1 1/2 cups all-purpose flour 🌾
- 1 1/2 cups old-fashioned rolled oats 🥣
- 3/4 cup cold unsalted butter, cubed 🧈
- 1/2 tsp salt 🧂
- 1 tsp ground cinnamon (optional) 🫙
- 1/2 tsp baking powder 🧁
instructions
- 1Preheat the oven to 375°F (190°C). Line a 9x9-inch (23x23 cm) baking pan with parchment, leaving an overhang for easy removal.
- 2In a medium bowl, toss the strawberries and rhubarb with the granulated sugar, cornstarch, lemon juice and vanilla until evenly coated. Set aside to macerate while you make the crust.
- 3In a large bowl, whisk together the flour, rolled oats, brown sugar, salt, cinnamon and baking powder.
- 4Cut the cold butter into the dry mixture using a pastry cutter, two forks, or your fingertips until the mixture resembles coarse crumbs with some pea-sized bits.
- 5Reserve about 1 1/2 cups of the oat-crumble mixture for the topping. Press the remaining mixture firmly and evenly into the bottom of the prepared pan to form the crust.
- 6Spread the strawberry‑rhubarb filling evenly over the crust, making sure juices are distributed.
- 7Sprinkle the reserved oat crumble over the fruit layer, covering as much as possible.
- 8Bake for 35–45 minutes, until the top is golden and the filling is bubbling at the edges. If the topping browns too quickly, tent loosely with foil for the last 10 minutes.
- 9Remove from the oven and let cool completely in the pan on a wire rack (this helps the filling set). Once cool, lift out with the parchment overhang and cut into bars.
- 10Serve at room temperature or slightly chilled. Store in an airtight container in the refrigerator for up to 4 days, or freeze individually wrapped for longer.