In the bowl of a food processor, combine flour, salt, and sugar. Add butter, and process until the mixture resembles coarse meal, 8 to 10 seconds.
With machine running, add ice water in a slow, steady stream through feed tube. Pulse until dough holds together without being wet or sticky; be careful not to process more than 30 seconds. To test, squeeze a small amount together: If it is crumbly, add more ice water, 1 tablespoon at a time.
Divide dough into two equal balls. Flatten each ball into a disk, and wrap in plastic. Transfer to the refrigerator, and chill at least 1 hour. Dough may be stored, frozen, up to 1 month.