# What You'll Need:
→ Crumble base & topping
01 - 1 1/2 cups all-purpose flour
02 - 1 1/2 cups rolled oats
03 - 3/4 cup granulated sugar
04 - 1/2 cup packed light brown sugar
05 - 1/2 teaspoon fine salt
06 - 1 teaspoon ground cinnamon
07 - 1 cup unsalted butter, melted (2 sticks)
→ Strawberry-rhubarb filling
08 - 2 cups fresh strawberries, hulled and diced
09 - 2 cups fresh rhubarb, diced
10 - 2/3 cup granulated sugar
11 - 2 tablespoons cornstarch
12 - 2 teaspoons vanilla extract
13 - 2 teaspoons fresh lemon juice
# How To Make It:
01 - Heat oven to 350°F. Line a 9x13-inch baking pan with parchment paper leaving an overhang for easy removal and set aside.
02 - In a large bowl, whisk together flour, rolled oats, granulated sugar, light brown sugar, salt and cinnamon until evenly distributed.
03 - Pour the melted butter over the dry mixture and stir with a spatula until a cohesive, coarse crumb forms, taking care not to overwork.
04 - Measure out 1 1/2 cups of the crumb mixture and set aside for the topping. Press the remaining crumbs firmly and evenly into the prepared pan to form a compact base.
05 - In a separate bowl, toss strawberries and rhubarb with granulated sugar, cornstarch, vanilla and lemon juice until the fruit is evenly coated and no dry starch remains.
06 - Spread the fruit mixture in an even layer over the pressed base, then distribute the reserved crumbs evenly over the fruit.
07 - Bake for 40 to 45 minutes, or until the topping is golden brown and the filling is bubbling at the edges. Rotate the pan halfway through baking if your oven has hot spots.
08 - Allow the pan to cool completely on a wire rack, then lift out using the parchment overhang and cut into 12 bars. Chill briefly if cleaner slices are desired.