Preheat the oven to 375°F (190°C). Measure and chop the rhubarb; hull and slice the strawberries. Place the chopped rhubarb and sliced strawberries in a large mixing bowl and add sugar, cornstarch, and a pinch of salt. Toss until the fruit is evenly coated, then transfer to a baking dish.
4 cups fresh rhubarb, chopped, 2 cups strawberries, sliced, 1 cup granulated sugar, 2 tablespoons cornstarch, pinch of salt
In a separate mixing bowl, combine flour, oats, and brown sugar. Add the cold, cubed butter. Use a pastry cutter or forks to cut the butter into the dry ingredients until the mixture resembles coarse crumbs with some pea-sized pieces.
1 cup all-purpose flour, 1/2 cup rolled oats, 1/2 cup brown sugar, 1/2 cup unsalted butter, cold
Sprinkle the crumble topping evenly over the fruit filling in the baking dish, covering all the fruit without pressing down too tightly.
1 cup all-purpose flour, 1/2 cup rolled oats, 1/2 cup brown sugar, 1/2 cup unsalted butter, cold
Bake in the preheated oven for about 40 minutes, or until the topping is golden brown and the filling is bubbling around the edges. The kitchen should fill with a sweet, fruity aroma.
Remove from the oven and allow to cool slightly before serving. The topping will be crisp, and the filling should be thick and glossy with visible steam or bubbling.
