Preheat oven to 350 degrees F. Grease an 8x8 baking dish.
Combine the almond flour, coconut flour, coconut oil, maple syrup, vanilla extract and salt in a medium-sized bowl.
Next, mix the sliced strawberries, rhubarb, maple syrup and corn starch together in a medium bowl until well coated. You can also sub in equal amounts of tapioca or arrow root starch for the cornstarch if you prefer.
Press half the crumble mixture into the bottom of the greased baking dish with the back of a spoon or spatula. (You may need to wet the back of the spoon or spatula to prevent it from sticking).
Next, evenly distribute the strawberry rhubarb mixture over top of the crumble mixture.
Evenly sprinkle the remaining crumble mixture over top of the strawberry rhubarb mixture.
Place it in the oven and bake for 30 minutes or until the crumb mixture on the top is golden.
Let it cool for at least half an hour before serving. This will allow the mixture to thicken up slightly. Serve by itself or with coconut whipped cream or ice cream if desired.