In the bowl of a food processor, pulse together the flour, sugar, and salt until combined. Add the shortening and pulse until pea-sized crumbs form. Transfer the dough to a large bowl and bring the dough together with a wooden spoon.
In a small bowl, whisk together the egg, vinegar, and water. Pour over the dough and mix until combined (dough will be sticky). Cover with plastic wrap and chill in the refrigerator for at least 1 hour before rolling.
For a hot pie (e.g. with a filling that needs to be baked), divide the chilled dough in half on a generously floured work surface. Roll half of the dough to ¼-inch thick and transfer to a 9-inch pie dish. Repeat with the second half of dough if the pie is covered. Bake as instructed in the recipe. Wrap any remaining dough in plastic wrap and store in the refrigerate.
For a cold pie (e.g. with a filling that doesn\’t need to be baked), move oven rack to the lowest tier and preheat oven to 375°F. Divide the chilled dough in half on a generously floured work surface. Roll half of the dough to ¼-inch thick and transfer to a 9-inch pie dish. Loosely fit aluminum foil over the lined pie dish and weigh down with pie weights, raw rice or uncooked beans. Bake for 25 to 30 minutes. Remove the weights and foil and continue baking for 10 to 12 minutes until golden brown. Fill and chill according to recipe.