Perfect Pie Dough, recipe follows Flour, for dusting Berry Pie Filling, recipe follows PERFECT PIE DOUGH: BERRY PIE FILLING: 1 1/2 cups mixed fresh raspberries and strawberries 1/4 cup plus 2 tablespoons sugar 1 1/2 tablespoons cornstarch 1 teaspoon fresh lemon juice 3/4 cup (1 1/2 sticks) unsalted butter, cut into small pieces, chilled 6 to 8 tablespoons ice cold water 1 egg, beaten Turbinado sugar, for dusting