Combine the flour, salt, and shortening in a food processor and pulse 8-10 times, or combine in a large bowl and use a pastry cutter to gradually work the shortening into the flour until it resembles coarse meal.
In a small bowl, beat the egg with a fork then pour it into the flour mixture and pulse. Slowly add in the ice water and vinegar, stirring together gently until all the ingredients are incorporated and the dough sticks together when pinched.
Divide the dough in half and form into balls; use a rolling pin to flatten each ball into a disc about ½ inch thick. Wrap in plastic wrap and place in the freezer until needed. (If you will be using the dough immediately, it’s still a good idea to place it in the freezer for 25 to 30 minutes to chill.)
When you are ready to use the dough, remove from the freezer. Between two sheets of parchment paper or on a generously floured surface, roll the dough, starting at the center and working your way out until the dough is approximately 2 inches larger than your pie plate. (Sprinkle some flour over the top of the dough if it’s a bit too moist.) Be gentle and patient; it'll take a little time to get the dough completely rolled out.
Using a spatula, carefully lift the dough from the surface of the counter into the pie plate (or you can roll the pastry over the rolling pin, lift it onto the pie plate, and unroll it). Lift the edges of the dough gently and allow the dough to settle naturally into the plate, fitting snugly along the bottom and sides without pressing or stretching (to avoid shrinking during baking). Trim any excess dough, leaving an overhang of about 1 inch. Go around the pie plate, pinching and tucking the dough under itself to create a clean edge.
If you are making a single-crust pie, crimp or flute the edges as desired, using a fork or your fingers. The crust is now ready to be par-baked 10-15 minutes) or filled, as your recipe specifies. If you are making a double-crust pie, roll out the remaining dough and use it to top your filling.
Egg replacement:
Mixing 1 ½ tablespoons oil, 1 ½ tablespoons water, and 1 teaspoon baking powder will give the same binding benefits of 1 egg. The more eggs you need, the more oil, water, and baking powder you should use. This is a great option if you don’t want to change the taste of the meal, but you still want to bind the ingredients together.
Using margarine instead of all-shortening:
1 stick of cold margarine + ½ cup shortening.
