Whole-wheat pastry flour is more finely milled than regular whole-wheat flour, making it ideal for pie crusts and other delicate baked goods.
Pulse flours, sugar, and salt in a food processor until combined, about 3 times. Add butter; pulse until mixture is crumbly, about 10 times. With processor running, add ¼ cup cold water and vinegar in a slow, steady stream, processing until a dough forms, about 20 seconds. Transfer to a lightly floured work surface. Shape into a 5-inch disk using floured hands. Wrap tightly in plastic wrap. Refrigerate until chilled, about 30 minutes. (Dough may be wrapped and stored in refrigerator up to 2 days before using.)
Variation: Vegan Whole-Wheat Piecrust Dough–Prepare recipe as directed, substituting vegan butter for unsalted butter, and adding up to 1 additional tablespoon cold water if needed to help dough come together.