Preheat the oven to 350℉
Make the crust: Grind the almonds in a food processor. Add the flour, sugar, butter or coconut oil, egg, baking powder, vanilla, and salt and pulse to combine. Transfer crust to a bowl.
Reserve ⅓ cup of the dough in the bowl for use in the topping, and press the remaining dough into the pie pan, going all the way up the edges. Set aside.
Make the topping: Into the bowl with the reserved dough, add the coconut oil, almond flour, gluten-free flour, sugar, blanched almonds, cinnamon, and salt. Transfer the mixture back to the food processor and pulse to combine, do not over-pulse! Set aside.
Make the filling: In a medium bowl, mix together the rhubarb, strawberries, sugar, flour, lemon juice, vanilla, and salt. Pour the filling over the crust.
Top the filling with the crumb topping. Grab fistfuls of topping to make big chunks that hold together - this is the best part, when it cooks you get big chunks of crumble.
Bake for 65 minutes, or until the fruit bubbles, the topping browns, and the crust is lightly golden but not overly brown! Check at the 55-minute mark - the baking time will differ based on your oven setting.