Step 2 – Mix 1 cup sugar, 3 tbsp flour, calafate and rhubarb together in a bowl. Place the mixture in a baking dish, then set aside.
Step 3 – In a bowl, mix the flour, brown sugar, butter and oatmeal together with your fingers until a crumble forms. Sprinkle the crumble over the fruit in the baking pan.
Step 4 – Bake for 30 minutes in a preheated oven or until the top is golden brown. Serve warm with vanilla ice cream.