Combine flour and salt in a large mixing bowl; cut in shortening with a pastry blender until mixture resembles coarse meal. Combine water, egg, and vinegar in a small bowl. Add liquid to flour mixture; stir with a fork until dry ingredients are moistened, shape dough into a ball; chill.
Divide dough into three equal portions. Roll each portion to 1/8- inch thickness on a lightly floured surface. Place each in a 9-inch pie plate; trim excess pastry around edges. Fold edges under, and flute. Prick bottom and sides of shell with a fork. Bake at 425° for 15 minutes or until golden brown.