Apricot Raspberry Pie

Place a baking sheet in middle of oven and preheat oven to 450°F. Whip together cornstarch, salt, and 1 cup plus 2 tablespoons sugar in a large bowl.
Roll out 1 piece of dough (keep remaining piece chilled) on a lightly floured surface with a lightly floured rolling pin into a 13-inch round and fit into a 9-inch glass pie plate (4-cup capacity). Trim edge, leaving a 1/2-inch overhang.
Chill shell while rolling out dough for top crust.
Roll out remaining piece of dough into an 11-inch round.
Stir apricots into sugar mixture until thoroughly mixed, then gently stir in raspberries and spoon filling into shell.
Cover pie with pastry and trim with kitchen shears, leaving a 1/2-inch overhang.
Crimp edge decoratively.
Brush egg on the top of the pie.
Sprinkle the remaining 2 tablespoons sugar all over it.
Cut 3 steam vents in top crust with a sharp small knife.
Bake pie on hot baking sheet 15 minutes.
Reduce oven temperature to 375°F and continue to bake until crust is golden brown and filling is bubbling, about 45 minutes more.
Cool pie on a rack at least 2 hours before serving.
Cooks' note:
Pie can be made 1 day ahead and kept at room temperature.