Crumbly Strawberry Rhubarb Bars

If you ask me, strawberry rhubarb bars are the perfect spring dessert.

These easy-to-make bars feature a buttery oat crust that doubles as a crumble topping. The filling is packed with fresh strawberries and tangy rhubarb, creating a sweet-tart combination that tastes like springtime.

The oat base holds everything together while adding a nice texture. A splash of lemon juice brightens up the fruit filling, and just enough cornstarch keeps it from getting too runny.

They’re great for potlucks, bake sales, or just keeping in the fridge for when you need something sweet. Plus, they slice up cleanly and travel well.

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What Kind of Rhubarb Should I Use?

Fresh rhubarb is your best bet for these bars, and you’ll find it in season during spring and early summer at most grocery stores and farmers markets. The stalks can range from green to deep red, and while the red stalks look prettier, the color doesn’t actually affect the flavor – both work equally well. When selecting rhubarb, look for firm, crisp stalks and avoid any that feel soft or look dried out at the ends. If you can’t find fresh rhubarb, frozen rhubarb is a solid backup option – just make sure to thaw it completely and drain off any excess liquid before using it in your filling.

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Options for Substitutions

This recipe is pretty forgiving, so here are some swaps you can make if you need to:

• Rhubarb: If rhubarb isn’t in season or you can’t find it, you can use all strawberries instead – just increase the strawberries to about 3 cups total. You might want to add an extra tablespoon of lemon juice to keep that tangy flavor.
• Butter: You can use coconut oil as a substitute, but make sure it’s solid (not melted) when you mix it with the dry ingredients. The texture will be slightly different but still tasty.
• Oats: Quick oats or old-fashioned rolled oats both work fine here. Just avoid instant oats as they’ll make the bars mushy.
• Brown sugar: If you’re out of brown sugar, mix 1/2 cup white sugar with 1 tablespoon of molasses. Or just use all white sugar – the bars will be a bit less chewy but still good.
• Cornstarch: You can swap cornstarch with the same amount of flour or tapioca starch for thickening the fruit filling.
• Vanilla essence: Almond extract works nicely here too – just use half the amount since it’s stronger.

Watch Out for These Mistakes While Baking

The biggest mistake when making fruit bars is using rhubarb that’s too watery, which can make your bars fall apart – be sure to dice the rhubarb into small, even pieces and avoid adding extra liquid to the filling.

Another common error is not pressing the bottom crust firmly enough into the pan, so use the back of a measuring cup or your hands to really pack it down for a solid base that holds together when you cut the bars.

To prevent a soggy bottom layer, make sure your fruit filling isn’t too runny by letting the cornstarch mixture coat the strawberries and rhubarb completely, and don’t skip the cooling time – these bars need at least an hour to set properly before cutting, or they’ll crumble apart.

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What to Serve With Strawberry Rhubarb Bars?

These bars are pretty sweet and tangy on their own, so they pair really well with a scoop of vanilla ice cream or some fresh whipped cream on the side. I love serving them with a hot cup of coffee or tea in the afternoon – the buttery oat topping is perfect for dunking if you’re into that. They also work great as part of a dessert spread at potlucks or barbecues alongside other fruit desserts, or you can pack them up for picnics since they travel well and taste amazing at room temperature. If you want to get fancy, drizzle a little extra cream or Greek yogurt on top for breakfast the next morning.

Storage Instructions

Store: Keep your strawberry rhubarb bars in an airtight container in the fridge for up to 5 days. I like to layer them between sheets of parchment paper so they don’t stick together. They actually taste even better the next day once all the flavors have had time to meld!

Freeze: These bars freeze really well for up to 3 months. Just wrap them individually in plastic wrap, then place them all in a freezer bag. That way you can grab just one or two whenever you need a sweet treat without thawing the whole batch.

Serve: You can enjoy these bars straight from the fridge when they’re nice and cold, or let them sit at room temperature for about 20 minutes if you prefer. If you’re pulling them from the freezer, just thaw them in the fridge overnight or on the counter for an hour or so.

Estimated Nutrition

Estimated nutrition for the whole recipe (without optional ingredients):

• Calories: 2100-2300
• Protein: 20-25 g
• Fat: 70-80 g
• Carbohydrates: 370-390 g

Ingredients

For the crumb layer:

• 1 1/2 cups flour (I always use King Arthur all-purpose flour)
• 1/2 tsp baking soda
• 1/4 tsp baking powder
• 1/4 tsp salt
• 1 1/3 cups oats
• 1/2 cup brown sugar
• 1/3 cup granulated sugar
• 3/4 cup butter (I like Kerrygold unsalted butter for this)
• 2 1/2 tsp vanilla extract

For the filling:

• 1 3/4 cups strawberries (hulled and sliced into 1/4-inch thick rounds)
• 1 1/2 cups rhubarb (trimmed and cut into 1/2-inch pieces)
• 1 tbsp lemon juice
• 1/3 cup sugar
• 1 1/2 tbsp cornstarch

Step 1: Prepare the Oven and Mise en Place

• 1 3/4 cups strawberries
• 1 1/2 cups rhubarb

Preheat your oven to 350°F and line a 9×13 inch baking dish with parchment paper for easy removal.

While the oven heats, prepare your fruit: hull and slice the strawberries into 1/4-inch thick rounds, then trim and cut the rhubarb into 1/2-inch pieces.

Having everything prepped before you start mixing ensures a smooth, efficient assembly process.

Step 2: Build the Oat Crust Base

• 1 1/2 cups flour
• 1/2 tsp baking soda
• 1/4 tsp baking powder
• 1/4 tsp salt
• 1 1/3 cups oats
• 1/2 cup brown sugar
• 1/3 cup granulated sugar
• 3/4 cup butter
• 2 1/2 tsp vanilla extract

In a large bowl, whisk together the flour, baking soda, baking powder, and salt.

Stir in the oats, brown sugar, and granulated sugar until evenly combined.

Melt the butter and mix it with the vanilla extract, then pour this mixture into the dry ingredients and stir until the mixture resembles wet sand with visible oat pieces throughout.

I like using quality butter like Kerrygold here because it really enhances the rich, buttery flavor of the base.

Step 3: Layer the Crust and Prepare the Filling

• oat mixture from Step 2
• 1 3/4 cups strawberries
• 1 1/2 cups rhubarb
• 1 tbsp lemon juice

Press two-thirds of the oat mixture firmly into the prepared baking dish, creating an even bottom layer that will support the fruit filling.

Set the remaining one-third of the oat mixture aside for topping.

In a separate bowl, toss the prepared strawberries and rhubarb with the lemon juice to coat evenly.

Step 4: Thicken the Fruit and Assemble

• fruit mixture from Step 3
• 1/3 cup sugar
• 1 1/2 tbsp cornstarch
• remaining oat mixture from Step 3

In a small bowl, whisk together the sugar and cornstarch until no lumps remain.

Toss this mixture with the lemon-coated fruit until evenly coated—the cornstarch will thicken the fruit juices as the bars bake, preventing a soggy bottom layer.

Spread the fruit mixture evenly over the crust, then crumble the reserved oat mixture over the top in an even layer, pressing down gently so it holds together.

Step 5: Bake Until Golden

Bake in the preheated 350°F oven for 45-50 minutes, until the top is golden brown and the fruit filling is bubbling slightly at the edges.

The bars are done when the crust is set and firm to the touch.

I always let the bars cool completely in the pan before cutting—this gives the cornstarch time to fully set and keeps everything from crumbling apart.

Step 6: Cool and Serve

Allow the bars to cool completely in the baking dish at room temperature for at least 2 hours (or until fully cooled).

Once cooled, use the parchment paper to lift the entire slab out of the dish, then cut into squares.

Serve as is or with whipped cream if desired.

Crumbly Strawberry Rhubarb Bars

Delicious Crumbly Strawberry Rhubarb Bars recipe with step-by-step instructions.

Print Recipe Pin Recipe

Prep Time 25 minutes mins

Cook Time 45 minutes mins

Total Time 1 hour hr 12 minutes mins

Servings 16 bars

Calories 2200 kcal

Ingredients

  

For the crumb layer

• 1 1/2 cups flour (I always use King Arthur all-purpose flour)
• 1/2 tsp baking soda
• 1/4 tsp baking powder
• 1/4 tsp salt
• 1 1/3 cups oats
• 1/2 cup brown sugar
• 1/3 cup granulated sugar
• 3/4 cup butter (I like Kerrygold unsalted butter for this)
• 2 1/2 tsp vanilla extract

For the filling

• 1 3/4 cups strawberries (hulled and sliced into 1/4-inch thick rounds)
• 1 1/2 cups rhubarb (trimmed and cut into 1/2-inch pieces)
• 1 tbsp lemon juice
• 1/3 cup sugar
• 1 1/2 tbsp cornstarch

Instructions

 

• Preheat your oven to 350°F and line a 9x13 inch baking dish with parchment paper for easy removal. While the oven heats, prepare your fruit: hull and slice the strawberries into 1/4-inch thick rounds, then trim and cut the rhubarb into 1/2-inch pieces. Having everything prepped before you start mixing ensures a smooth, efficient assembly process.
• In a large bowl, whisk together the flour, baking soda, baking powder, and salt. Stir in the oats, brown sugar, and granulated sugar until evenly combined. Melt the butter and mix it with the vanilla extract, then pour this mixture into the dry ingredients and stir until the mixture resembles wet sand with visible oat pieces throughout. I like using quality butter like Kerrygold here because it really enhances the rich, buttery flavor of the base.
• Press two-thirds of the oat mixture firmly into the prepared baking dish, creating an even bottom layer that will support the fruit filling. Set the remaining one-third of the oat mixture aside for topping. In a separate bowl, toss the prepared strawberries and rhubarb with the lemon juice to coat evenly.
• In a small bowl, whisk together the sugar and cornstarch until no lumps remain. Toss this mixture with the lemon-coated fruit until evenly coated—the cornstarch will thicken the fruit juices as the bars bake, preventing a soggy bottom layer. Spread the fruit mixture evenly over the crust, then crumble the reserved oat mixture over the top in an even layer, pressing down gently so it holds together.
• Bake in the preheated 350°F oven for 45-50 minutes, until the top is golden brown and the fruit filling is bubbling slightly at the edges. The bars are done when the crust is set and firm to the touch. I always let the bars cool completely in the pan before cutting—this gives the cornstarch time to fully set and keeps everything from crumbling apart.
• Allow the bars to cool completely in the baking dish at room temperature for at least 2 hours (or until fully cooled). Once cooled, use the parchment paper to lift the entire slab out of the dish, then cut into squares. Serve as is or with whipped cream if desired.