Makes two batches for our Peach-Raspberry Slab Pie.
Process flour, salt, and sugar in a food processor until combined. Add butter. Process until mixture resembles coarse meal, about 10 seconds. With machine running, add ice water in a slow, steady stream just until dough comes together. (Do not process more than 30 seconds.)
Turn dough out onto a piece of plastic wrap. Flatten dough, and shape into a rectangle. Wrap in plastic. Refrigerate at least 1 hour (or overnight).
Dough can be frozen for up to 1 month.