In a food processor, combine flour, salt, and sugar; pulse to combine. Add butter; pulse until mixture resembles coarse meal, with just a few pea-size pieces of butter remaining.
Sprinkle with 1/4 cup ice water. Pulse until dough is crumbly but holds together when squeezed with fingers (if necessary, add up to 1/4 cup more water, 1 tablespoon at a time). To help ensure a flaky crust, do not overprocess.
Transfer half of dough (still crumbly) onto a piece of plastic wrap. Form dough into a disk 3/4 inch thick; wrap tightly in plastic. Refrigerate until firm, at least 1 hour (and up to 3 days). Repeat with remaining dough. Makes 2 disks.
Disks can be frozen, tightly wrapped, up to 3 months. Thaw before using.