Preheat your oven to 425°F (220°C) and grab a large mixing bowl. Whisk together sugar and flour until well combined. Add in the sliced rhubarb and strawberries, tossing gently to coat the fruit thoroughly. Once coated, transfer the fruity mixture into a greased 11×7-inch baking dish. For an extra touch of flavor, dot the filling with a few small pieces of butter.

In a separate bowl, combine all-purpose flour and salt, mixing until evenly blended. In another bowl, whisk together the canola oil and warm water. Gradually pour this wet mixture into the flour mixture, stirring until a sticky dough forms.

To shape your crust, roll out the sticky dough between two sheets of wax paper until it forms an 11×7-inch rectangle. Carefully flip the rolled dough over the prepared fruit filling, peeling off the wax paper.

Brush the top of the crust with milk to achieve a golden color as it bakes. Sprinkle granulated or coarse sugar over the crust for a delightful crunch. Place the baking dish in the preheated oven and bake for 40-50 minutes.

Once baked, remove the Strawberry-Rhubarb Cobbler from the oven and let it cool for about 10 minutes before serving.