Preheat oven to 425 degrees. In a large plastic bowl, sift together all dry ingredients. Add 1/2 cup of shortening and cut it in with a pastry blender or with your hands. Work all of the fat into the flour mixture until fine crumbles form.
Add the rest of the shortening and cut it again. Make sure it is evenly and fully blended in. It should form larger crumbles this time.
In a small bowl, whisk egg, ice water, and vinegar.
Add the egg mixture into the flour mixture. Use your hands to fold the ingredients together. DO NOT OVER MIX. Mix just until the dough comes together.
Divide the dough into halves and form a ball with each half. Push the dough down to compress the cracks. Cover the half you aren't working with with plastic wrap so it doesn't dry out. Flour a large surface and a rolling pin. Slowly roll out the dough. Smooth out any cracks. Roll the dough until it is 2 inches larger in diameter than the pie plate. It should be about 1/4 inch thick.
Use the rolling pin to roll up the pie dough and transfer it to the pie dish. Don't stretch the dough. Gently mold the crust into the pie plate. Trim edges with a butter knife. Press the dough so that it extends slightly past the edges of the plate because it will shrink a little while baking.
Add your top crust or decorations as desired. (See note below about top crust and decorations) Bake for 35-40 minutes or until crust is golden brown and filling is bubbly. If pre-baking the crust, poke holes in the crust with a fork and bake for 10-12 minutes.
If you are using a top crust or decorating with crust, brush the dough with a little milk and sprinkle some sugar over the top before baking. If you are using a full top crust, make sure to crimp the sides and cut a few slits in the top for air to escape. This recipe makes enough dough for 2 pie crusts, or 1 double crust PLUS a little extra. Use the extra for decorations or hand pies.