1. Preheat oven to 375F.
2. In a large bowl combine apple slices, sugar, flour, cinnamon, nutmeg, salt, and lemon juice. Place mixture into pie crust.
3. On a lightly floured surface roll remaining pastry dough and cut into strips. Place strips on top of apple pie making a crisscross pattern.
4. Mix the egg yolk and water in a small bowl and lightly brush the top of the pie.
5. Bake for approximately 45 minutes.
Serve warm topped with custard or whipped cream.