Add the chopped strawberries and rhubarb to a large mixing bowl. Mix the orange juice, cornstarch and maple syrup together until combined and then add to the mixing bowl, tossing everything together.
In a food processor, add all the crisp topping ingredients and pulse until crumbly. You can alternatively use a bowl and your hands, pressing until you get a crumbly mixture.
Pour the fruit mixture into an 8×8 inch baking dish then add the crumble topping.
Bake for 45-50 minutes, then remove from the oven and let cool for at least 15 minutes before serving.