Combine sugar substitute, cornstarch, lemon rind, lemon juice, nutmeg, cinnamon, and apple slices
Place in 9 inch deep dish pie plate on baking dish; set aside
Combine flour and salt; cut in margarine until mixture resembles cornmeal
Blend in water with fork until all dry ingredients are moistened
Shape dough into a ball. Roll out dough on floured surface, and place on top of apple filling
Bake at 425 degrees for 35 minutes or until brown.
For a professional touch, brush crust with a mixture of egg and milk