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). Form the dough into a disc shape and wrap securely with plastic wrap. Chill it 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 0.25-inch thick and transfer to a 9-inch pie dish. Repeat with the second half of the dough if the pie is covered.

Bake as instructed in the recipe. Wrap any remaining dough in plastic wrap and store in the refrigerator.

For a cold pie (e.g. with a filling that doesn't need to be baked), divide the chilled dough in half on a generously floured work surface. Roll half of the dough to 0.25-inch thick and transfer to a 9-inch pie dish.

Continue by following the instructions of your cold pie recipe. Wrap any remaining dough in plastic wrap and store in the refrigerator.