Mix flour, salt, and cold butter to create a coarse mixture; hydrate with cold water and form a dough. Chill for 2 hours.
Roll out one dough disc, line a pie dish, and trim excess, leaving a 1-inch overhang.
Toss apples, cherries, sugar, cornstarch, cinnamon, and vanilla to coat; fill the pie dish with the mixture.
Roll out the second dough disc, cut strips for a lattice top, and braid some strips for decoration.
Arrange lattice over the filling, crimp edges, brush with egg wash, and sprinkle sugar.
Bake at 425°F for 15 minutes, then at 350°F for 50-55 minutes until golden and bubbling.
Cool the pie for 1-2 hours before serving.