Combine flour, baking powder, salt, and sugar in a large bowl; cut in shortening with pastry blender until mix resembles coarse meal. Stir in egg, water, and vinegar.
Divide dough into 5 equal parts; shape each into a ball and wrap tightly. Chill. May be stored up to 2 weeks in refrigerator. To fit into a pie plate, roll each ball of dough to 1/8 inch thickness on a lightly floured surface.
Place in a 9 inch pie plate; trim off excess pastry along edges. Fold edges under and flute. For baked pastry shell, prick bottom and sides of pastry generously with a fork. Bake at 450° F.
Servings: five 9 inch pies