Blend flour, salt, and sugar together in a large bowl. Cut butter and shortening into 1/2-inch cubes and add to flour mixture. Using a pastry blender or 2 knives, cut into dry mixture until it is the con- sistency of coarse meal.
Then gradually sprinkle 3 tablespoons cold water over flour mixture, using a fork to work liquid into dry ingredients. Then work in just enough remaining cold water, 1 tablespoon at a time, so dough can be gathered into a firm ball.
Flatten ball slightly with the palm of your hand. Wrap pastry and refrigerate at least until chilled, about 30 minutes. Pastry will keep well for several days. It also freezes well.