In the bowl of a food processor, add flour and salt. Pulse to combine. Add butter and pulse several times until butter is the size of large chunks. Alternatively, place flour in a large bowl and add salt. Add butter and using your fingers or a pastry blender, blend into butter until the size of large peas.

Pour the vinegar and beaten egg into the bowl and pulse to combine (or combine with a fork if not using a food processor).

With the food processor running, slowly add water through the chute, a few tablespoon at a time. You may not need the full amount of water, depending on your climate. When the mixture comes together in the bowl, stop mixing. Of note, gluten free pie crusts do better when they are slightly wetter (because the flour will soak up some of the liquid).

Divide the dough between two sheets of plastic wrap, flattening each into a round disk. Chill in the refrigerator for about 20-30 minutes.

Roll out the dough onto a lightly floured surface into approximately a 12-inch round, moving constantly to avoid sticking. If it does stick, lightly sprinkle more flour. Roll dough onto rolling pin and carefully lift and unroll into the pie plate. Trim the edges of the dough and crimp the edges.

Prick the bottom and sides of the dough all over with a fork. Place the crust in the refrigerator and chill for at least 30 minutes.

Preheat the oven to 425° F. Remove the pie crust from the refrigerator and line it with heavy duty foil (my preferred method) or parchment paper. Fill it with pie weights, beans, rice, any combination of those, or granulated sugar (it will get slightly toasted and you can use it again for recipes).

Bake for approximately 12-15 minutes, or until the edges look set, but are still "blonde". Carefully remove the foil and beans and continue to bake for about 5 more minutes, or until the bottom and sides are no longer shiny. Cool the crust completely before proceeding with your recipe.

Roll out the bottom crust and add your filling of choice into the crust. Roll top crust out and place on top of filling. Crimp as desired to seal. Vent and proceed as per your recipe instructions.