In a large bowl or the bowl of a food processor, stir together the flour, sugar and salt. Add the butter and shortening and use a fork, pastry blender, wire whisk or the “pulse” motion of the food processor to blend the mixture until it resembles coarse meal, with lumps of fat no bigger than a pea.
Drizzle the minimum amount of water over the mixture and stir until the dough comes together, adding a little more a bit at a time if you need it. Gather the dough into a ball, flatten it into a disc, wrap it in plastic and chill it for at least half an hour. If you are making a double crust pie, divide the dough in half, making one half slightly larger than the other.
(Your pastry can be prepared up to this point and frozen for up to 4 months; let it thaw on the countertop when you need it.