- 1 1/2 cups sugar
- 5 tablespoons quick-cooking tapioca
- 1/2 teaspoon coarse salt
- 3 pounds peaches, peeled and sliced (6 cups)
- 12 ounces blueberries (2 cups)
- 3 tablespoons fresh lemon juice (from 1 lemon)
- All-purpose flour, for rolling
- 1 homemade or store-bought double-crust pie dough
- 1 large egg, separated, white lightly beaten
- 2 tablespoons cold unsalted butter, cut into small pieces
- Preheat oven to 425 degrees. In a large bowl, whisk together sugar, tapioca, and salt. Add peaches, blueberries, and lemon juice and toss to combine; let sit 15 minutes. Lightly flour a rolling pin and work surface and roll out half the dough to a 12-inch round. Place in a 9-inch glass pie plate and brush with egg white. Pour in fruit filling and dot with butter.
- Roll out remaining dough to a 12-inch round and place over fruit filling. Trim excess and crimp edges to seal. In a small bowl, lightly beat egg yolk with 1 tablespoon cold water. Brush top of dough with egg yolk mixture. With a paring knife, cut several small slits on top to vent. Set on a rimmed baking sheet and bake until crust is deep golden brown and juices are bubbling, about 50 minutes. (Tent loosely with foil if crust browns too quickly.) Let pie cool completely on a wire rack, about 3 hours.
Store, covered, up to overnight.