Make your favorite pastry for a 9" 2-crust pie.
Preheat oven to 425F
2 tbsp. lemon juice
2 cups sliced peaches
2 cups blueberries
1 cup sugar
2 tbsp. quick cooking tapioca
2 tbsp. butter
1 egg yolk
Sprinkle lemon juice over fruit in a large bowl.
Mix sugar, tapioca and salt, toss lightly with fruit.
Let stant 15 minutes.
Turn onto pastry lined pie plate, mounding in center.
Dot with butter
Cover with top crust and pinch edge diagonally all around.
Brush top with egg yolk beaten with 1 tbsp. water.
Bake 45 minutes or until fruit is tender and crust is golden.