Pulse together flour, salt, and butter in a food processor with dough blade just until mixture resembles coarse meal with some roughly pea-size butter lumps.
Drizzle 3 tablespoons ice water evenly over mixture and pulse in processor until incorporated.
Squeeze a small handful: If it doesn’t hold together, add more ice water, 1/2 tablespoon at a time, pulsing until incorporated, then test again. Try not overwork dough or pastry will be tough.
Turn dough out onto a lightly floured surface. Gather dough together and press into a 5-inch disk. Chill, wrapped in plastic wrap, until firm, at least 1 hour.