Mash the apples slightly in a bowl.
Mix in the flour, sugar and salt.
Beat the egg in a small bowl; beat in the vanilla.
Stir the egg mixture into the apple mixture.
Stir in the sour cream.
Pour into the pie shell.
Bake at 350 degrees for 40 minutes.
Remove from oven.
Sprinkle with Cinnamon Topping.
Return to oven and bake for 15 minutes longer.