For the pie crust: In the bowl of a food processor, combine the flour, salt, sugar and butter; pulse until the mixture resembles a coarse meal. Add cold water, 1 tablespoon at a time, and pulse until the dough is crumbly yet holds together when squeezed. Divide into two disks, wrap in plastic and refrigerate until firm, about 1 hour.
For the cherry filling: In a large bowl add the sour cherries, sugar, salt, cornstarch and lemon juice. Mix to combine. Set aside.
On a floured surface, roll the chilled disks of pie dough into 14-inch rounds; wrap one around a rolling pin and gently place it (without stretching) in a 9-inch pie pan. Using kitchen shears, trim the edges to fit over the sides of the pie pan. Fill with the cherry pie filling.
For the lattice crust, cut the remaining rolled pie crust into 1-inch strips¿you should have enough for 10 strips. Lay 5 parallel strips on top of the pie filling, leaving 1/2 inch between each strip; fold back every other strip.
Place one long strip perpendicular to the parallel strips. Unfold the folded strips over the perpendicular strip. Take the strips underneath the perpendicular strip and fold them back. Lay down a second perpendicular strip next to the first one and, again, unfold the folded parallel strips. Repeat with the remaining perpendicular strips. Crimp the strips of dough down and under to seal the crusts together.
Brush the crust with egg wash. Place the pie in the oven and bake until the crust is golden, 1 hour. Remove to a wire rack and let cool for 1 hour before serving. Serve with scoops of vanilla ice cream rolled in sprinkles.