- 4 cups chopped rhubarb
- 1 1/2 cups fresh blueberries
- 1 cup chopped fresh strawberries
- 2 tablespoons lemon juice
- 2 tablespoons small pearl tapioca, or more as desired
- 1 cup raw sugar
- 1/4 cup butter
- 1/2 cup all-purpose flour
- 2 tablespoons raw sugar
- 1 pinch salt
- 1 pinch ground cinnamon
- 2 tablespoons water, or as needed
- Preheat oven to 400 degrees F (200 degrees C). Butter a 2 1/2-quart baking dish.
- Stir rhubarb, blueberries, strawberries, lemon juice, pearl tapioca, and 1 cup raw sugar in a bowl. Transfer to prepared baking dish.
- Place butter into a separate bowl and chop into small pieces with a pastry cutter. Cut in flour, 2 tablespoons raw sugar, salt, and cinnamon; stir in water, 1 tablespoon at a time, until the dough holds together. Drop small pieces of the dough on the fruit.
- Bake in the preheated oven until the filling is bubbly and the cobbler is lightly browned, 40 to 50 minutes. Allow to stand 10 minutes before serving.