Preheat oven to 350°F (175°C). Butter an 8 x 8-inch baking dish; set aside.
Prepare Fruit:
Mix rhubarb, strawberries, sugar, lemon juice, cornstarch, cinnamon, and a pinch of salt together in a large bowl. Set aside.
Prepare Topping:
Whisk together oats, flour, pecans, and sugar in a medium bowl.
Assemble + Crisp:
Transfer strawberry-rhubarb mixture to buttered baking dish.
Sprinkle oat mixture over fruit.
Using a small spoon, drizzle butter evenly over oat topping.
Bake crisp until topping is browned and fruit is bubbling, about 45 to 50 minutes.
Let cool at least 30 minutes before serving. Serve plain or topped with ice cream. Enjoy!
Notes
I used light brown sugar, although dark brown sugar would also work.For a vegan / dairy free crumble, use plant based butter.For a gluten free crisp, replace the all-purpose flour with almond meal.If you'd prefer to make this dessert with an oat-free topping, feel free to substitute my easy Crumble Topping. You'll love it either way!Make sure to read the info before this recipe card for helpful tips, variations, related recipes, and more!