1. Prepare the Crust

• Rest the Dough: Make the pie crust ahead of time and let the dough rest in the refrigerator. Divide into two disks.
• Preheat Oven: Position a rack in the lower third of the oven and preheat to 425°F (220°C).

2. Prepare the Filling

• Drain and Mix: Drain the sour cherries, reserving ½ cup (120 ml) of the juice. In a large bowl, mix cornstarch, salt, cherries, sugar, lemon juice, reserved cherry juice, and vanilla extract.

3. Assemble the Pie

• Roll the Bottom Crust: Roll out one dough disk on a floured surface to a 12-inch (30 cm) round. Transfer to a 9-inch (23 cm) pie dish, leaving about a ½-inch (1.3 cm) overhang. If using egg white, brush it over the crust to create a seal.
• Add Filling: Spoon the cherry filling into the crust, slightly mounding in the center.

4. Create the Top Crust

• Lattice Option: Roll out the second dough disk to a 12-inch (30 cm) round. Cut ten ¾-inch-wide (2 cm) strips using a knife or pastry wheel. Lay strips over the filling in a lattice pattern, trimming overhang to ½ inch (1.3 cm). Fold the bottom crust up over the lattice ends and crimp to seal.
• Full Top Option: Roll out the second disk as a full round. Lay it over the filling, trim edges, seal, and crimp. Slash decoratively to allow steam to escape.

5. Brush and Sprinkle

• Brush the top crust with milk and sprinkle with sugar.

6. Bake

• Place the pie on a rimmed baking sheet to catch any drips. Bake at 425°F (220°C) for 15 minutes. Reduce oven temperature to 375°F (190°C) and bake for about 1 hour longer, or until the filling is bubbling and the crust is golden brown. If the edges brown too quickly, cover with foil.

7. Cool and Serve

• Cool the pie completely on a wire rack before serving.