Preheat the oven to 375 degrees Fahrenheit. Line an 8-inch baking pan with parchment paper.
In a large mixing bowl, combine the rolled oats, brown sugar, and flour. Add vanilla extract and coconut oil. Mix until all ingredients are well combined and clumps begin to form.
1 1/2 cups rolled oats, 1 cup gluten-free flour, 1/3 cup packed brown sugar, 2 teaspoons vanilla extract, 1/2 cup melted or very soft coconut oil
Press the mixture into the bottom of the prepared pan evenly, reserving about 3/4 cup for the crumble topping.
Add the diced strawberries, tapioca starch (tapioca flour), lemon juice and sugar to a bowl and gently mix to coat the strawberries.
1 lb. fresh strawberries, 2 teaspoons tapioca starch, 3 tablespoon lemon juice, 1 tsp lemon zest, 1 tablespoon cane sugar
Pour strawberry mixture over bottom crust in pan and spread into an even layer.
Take the remaining oat mixture and sprinkle it over the strawberry filling.
Bake for 45-50 minutes, or until the strawberries have cooked and are bubbly. The crumble should be a light golden color.
Let the bars cool for a minimum of one hour before removing them from the pan. Once cooled, slice into 16 squares and enjoy.