01 - Preheat the oven to 350°F.
02 - In a large bowl, toss strawberries, rhubarb, granulated sugar, cornstarch, vanilla extract, and lemon zest until evenly coated.
03 - Pour the fruit mixture into a lightly greased 9-inch baking dish.
04 - In a separate bowl, whisk together flour, oats, brown sugar, cinnamon, and salt. Add cold butter and rub into dry ingredients with fingertips or pastry blender until coarse crumbs form.
05 - Sprinkle the crumble mixture evenly over the fruit filling.
06 - Bake for 35 to 40 minutes until topping is golden brown and fruit bubbles at the edges.
07 - Let cool for 10 minutes. Serve warm with scoops of vanilla ice cream.