Preheat oven to 350F/175C. In a large mixing bowl combine the rhubarb, strawberries, sugar, corn starch, lime and vanilla extract. Mix together to combine. Let sit for 10 minutes.
In a separate smaller mixing bowl combine the oats, almond flour, shaved almonds, sugar, cinnamon, cardamom, and sea salt. Stir to combine. Pour in the melted coconut oil and mix together.
In a 9x6 baking dish, pour in the sweet fruity mixture. Sprinkle with the crumble topping in an even layer. Bake for 45 minutes to 1 hour. Or, until the fruity sides are thick and bubbly, and the top is golden brown. Let rest for 20 minutes before serving. Serve warm or at room temperature, optional to serve with vegan ice cream or coconut yogurt.