Preheat oven to 375°F degrees.
In a large bowl, combine the sugar, flour, strawberries, and rhubarb. Place the mixture in a 9 x 13 baking dish.
In a separate bowl, mix flour, brown sugar, oats, cinnamon, and salt with a whisk to remove lumps and combine well. Stir in melted butter with a fork, fluffing as you mix.
Using your hands, evenly sprinkle the crumble topping over the fruit.
Bake for 45 minutes or until it is bubbling and the topping is lightly browned.
Allow to cool for 20 minutes and serve warm or at room temperature with a side of vanilla ice cream.
Store leftovers in the refrigerator for up to 3 days.