- 1/4 cup white sugar
- 1/4 cup light brown sugar
- 1/4 cup quick-cooking tapioca
- 1/4 teaspoon salt
- 3 cups diced rhubarb
- 3 cups fresh blueberries
- 1 pastry for a 9-inch double crust pie
- Preheat oven to 400 degrees F (200 degrees C).
- Stir white sugar, brown sugar, tapioca, and salt together in a large bowl. Add rhubarb and blueberries; toss to coat.
- Divide the pie dough in half and roll each half out into a 9-inch round. Place 1 round of dough in the bottom of a pie plate. Pile rhubarb-blueberry mixture on top of the dough and top with the remaining dough round. Trim excess dough from the top crust to leave a 1/2-inch border below the top rim of the pie plate. Tuck the top edges of the crust under the bottom crust and crimp border together. Place pie plate on a rimmed baking sheet.
- Bake in the preheated oven for 20 minutes. Reduce oven temperature to 350 degrees F (175 degrees C) and continue baking until the crust is golden brown and the filling is bubbling, 25 to 30 minutes more. Cool for 2 hours.