Preheat the oven to 350°F and line an 8x8-inch baking pan with parchment paper. Lightly spray the exposed pan sides with nonstick cooking spray.
Make the fruit filling: In a medium bowl, mix together the strawberries, rhubarb, cornstarch, lemon juice, maple syrup, and vanilla.
Make the crumble: In a food processor, combine the oats, nuts, almond flour, brown sugar, flaxseed, cinnamon, and salt and pulse until just combined. Add the coconut oil and pulse again. Add the water and pulse again. Press ⅔ of the crumble into the baking pan to form a crust. Bake 20 to 25 minutes or until golden brown and firm. Remove from the oven and let cool for 15 minutes.
Spread the fruit filling over the crust, sprinkle with the remaining crumble, and garnish with some rolled oats. Bake for an additional 20 minutes, or until the fruit is soft and the crumble topping is lightly crisp. Let cool completely before slicing. If not serving the same day, store the bars covered in the refrigerator.
Recipe by Love and Lemons at https://www.loveandlemons.com/strawberry-rhubarb-crumble-bars/