Add the cold butter, and mix with a pastry blender, a fork, or two knives until the butter is the size of peas.
Drizzle about 2 tablespoons of water over the dough mixture. Continue mixing, adding about a tablespoon of water at a time until the dough begins to come together in large clumps. (You may not need all of the water.) Do not over-mix.
Divide the dough in half, and wrap each half well in plastic wrap. Refrigerate at least 2 hours and up to 5 days.
To mix in the food processor
Place the flour, sugar, and salt in the bowl of the food processor. Pulse a few times to mix.
Add the butter, and pulse several times until the butter is the size of large peas.
Drizzle about half of the water over the dough mixture. Cover and turn on the food processor, and gradually add more water through the tube on top until the dough begins to come together. Do not over-mix.
Divide the dough in half, and wrap each half well in plastic wrap. Refrigerate at least 2 hours and up to 5 days.
Notes
*The sugar is optional if you don't want that bit of sweetness in your crust.