In a food processor combine flour, sugar, and salt and pulse several times.
Add butter cubes and pulse until mixture resembles coarse crumbs.
In a liquid measuring cup combine water, vinegar, and enough ice cubes to reach 1 cup.
Add liquid to the flour mixture (strain the ice so that it stays in the measuring cup) 2 tablespoons at a time, pulsing after each addition, until mixture resembles streusel (it will not come together like a dough, it will be somewhat dry but should stick together when you smoosh some of it between your fingers).
Shape dough into a ball with your hands. Divide in half and place each half on a large piece of plastic wrap. Pat into a 1/2-inch thick disc and wrap tightly in plastic wrap. Place in the freezer for 20 minutes.
Unwrap one pie crusts and roll into a 12-inch circle.
Gently press crust into the bottom of your pie dish. Fill as desired and cover with second crust if called for. See note for freezing second crust or using second crust for pie decoration.
*As written, this recipe makes two shortbread pie crusts which is great for a double-crusted pie (like this apple pie with one crust on bottom and one on top) OR a single crusted pie with pie crust dough for decorating (like this pumpkin pie). If you only need one crust, you can divide the recipe in half OR better yet, freeze one of the crusts for later - simply thaw and roll out when ready to use!Using second crust for pie decor: Cut shapes from the second crust, place on a baking sheet and brush with egg wash and sprinkle generously with sugar. Bake at 350 for 10 minutes. Cool and decorate baked pie.