With fork, mix together flour, sugar, and salt. Add shortening and mix with fork until ingredients are crumbly. In small bowl, beat together water, vinegar and egg. Combine the two mixtures, stirring with a fork until all ingredients are moistened. Divide dough into 5 portions and, with hands, shape each portion into a flat, round patty ready for rolling. Wrap each in plastic wrap and chill at least 1/2 hour. When ready to roll piecrust, lightly flour both sides of patty and place on a piece of plastic wrap. Place another piece of plastic wrap on top and, keeping pastry round, roll from center to 1/8 inch thickness and 2 inches larger than inverted pie pan. transfer to pie pan and fit loosely in pan. press with fingers to remove air pockets. Bake as desired. dough can be left in refrigerator up to 3 days, or it can be frozen until ready to use. Also makes 20 tart shells. No matter how much you handle this dough, it will always be flakey, tender and delicious. Makes five crusts.