Strawberry Rhubarb Bars

Make Strawberry Rhubarb Bars: buttery oat crust, jammy strawberry-rhubarb filling, and a crunchy crumble. Bake and share.

Ingredients

• 2 cups all-purpose flour (240g)
• 2 cups old fashioned rolled oats (224g)
• ¾ cup packed light brown sugar (165g)
• ¾ cup granulated sugar (150g)
• 1 teaspoon salt
• ¾ teaspoon baking soda
• ¾ cup unsalted butter (melted (170g))
• 2 teaspoons vanilla extract
• 2¼ cups diced strawberries (from 1 pound/450g)
• 2 cups diced rhubarb (¼-inch pieces/225g)
• ⅔ cup granulated sugar
• 2 tablespoons cornstarch
• 1 tablespoon fresh lemon juice

Instructions

Step 1: Preheat and combine the crumb ingredients

Preheat the oven to 350°F and prepare a 9x13-inch pan by buttering it or spraying it, then line it with parchment so the paper forms two opposite overhang “handles.” In a large mixing bowl whisk together the all-purpose flour, rolled oats, light brown sugar, granulated sugar, salt, and baking soda until evenly distributed. Stir together the melted butter and vanilla, pour into the dry mixture, and gently fold until the mixture is uniformly moistened but still slightly crumbly and granular—think coarse sand with buttery clumps.

Step 2: Press the crust and reserve the topping

Measure roughly two-thirds of the crumb mixture and press it into an even, compact layer across the bottom of the prepared rectangular pan, smoothing the surface with the back of a spoon or your palm so it’s level. Squeeze the remaining third of the mixture in your palm to form clumps, then break them into irregular pebble-like clusters and set them aside in a small bowl—these will become the crunchy, rustic topping.

Step 3: Make the filling and assemble the bars

Whisk together the granulated sugar and cornstarch in a medium bowl until pale and lump-free, then add the diced strawberries, diced rhubarb, and the fresh lemon juice; stir just until every piece of fruit is glossy and dusted in the sugar-cornstarch mix and a little pink syrup begins to form. Spread this fruit mixture in an even layer over the pressed crust so the bright pink and coral chunks peek through, then scatter the reserved crumb clumps across the top in an even, textured blanket—some clusters larger, some smaller—so the filling will bubble through as it bakes.

Step 4: Bake, cool, and slice for serving

Bake the assembled pan until the crumb topping is golden brown and the filling is visibly bubbling along the seams, about fifty to fifty-five minutes; remove from heat and let cool completely on a wire rack in the pan so the filling sets. Use the parchment “handles” to lift the whole slab from the pan, place on a cutting board, and slice into square bars with clean strokes so each piece retains its square geometry and the layered profile of crust, vivid pink filling, and crunchy oat topping. Store cooled bars in an airtight container in the refrigerator for up to five days.

Notes

• Use room temperature butter for even mixing.
• Line the pan with parchment for easy removal and cleaner slices.
• Thaw and drain frozen strawberries well to avoid excess moisture.
• Reduce sugar slightly if your fruit is very sweet.
• Freeze individual bars for easy grab-and-go snacks.