Yield: 16 squares
1 cup / 80 grams rolled oats
3/4 cup / 95 grams all-purpose flour
1/2 cup / 95 grams dark brown sugar
1/4 teaspoon fine grain sea salt
6 tablespoons /85 grams unsalted butter, melted
1 teaspoon cornstarch
1 tablespoon / 15 grams granulated sugar
1 cup / 125 grams diced rhubarb
1 cup / 155 grams diced strawberries (I cut average-sized berries in half, then each half in quarters)
Heat oven to 375 degrees F. Grease an 8-by-8-inch square baking pan and set aside.
Measure the oats, flour, brown sugar and salt into a medium mixing bowl and stir to combine. Pour the melted butter over and stir until it gets clumpy. Set aside 1/2 cup of the mixture and press the rest evenly into the bottom of the pan.
Softly toss the rhubarb and strawberries together in a bowl to combine. Spread the fruit mixture over the crust and sprinkle it evenly with cornstarch and granulated sugar. Scatter the reserved crumble mixture over the fruit and bake for 30 to 40 minutes, until the fruit is bubbling and the top crisp is golden.
Let the baked concoction cool in the pan. Once fully cooled, loosen up the edges with a cookie spatula. You can either cut into squares in the pan, or if you’re super-snazzy you can flip them out onto a cutting board.
Store leftovers in the fridge.