In a food processor, whirl together flour, sugar, and salt. Add butter and pulse into pea-size pieces. Drizzle 2/3 cup very cold water over crumbs and pulse just until evenly moistened. Turn dough out onto a work surface and gather into a ball, turning dough to combine any dry crumbs.
Wrap dough in plastic wrap, then press into a disk about 1 in. thick. Chill dough at least 1 hour and up to 2 days.
Set dough on a lightly floured work surface and divide in half. With a lightly floured rolling pin, roll 1 half to form a round 1/8 in. thick and at least 14 in. wide; lift and turn dough occasionally, dusting underneath with more flour.
Fold dough round in half, lift gently without stretching, and lay folded edge across center of a 9 1/2- to 10-in. deep-dish pie pan. Unfold and ease dough into pan. Trim edge evenly 1 in. beyond pan rim; discard scraps. Fold edge under itself so it's flush with and resting on top of rim.
For a lattice top: On a piece of parchment paper, roll out remaining half of dough the same way. Cut dough into strips 1/2 in. to 3/4 in. wide. Transfer strips on parchment to a large plate and chill.