Lightly spoon flour into dry measuring cups, and level with a knife. Combine 1/2 cup flour, water, and vinegar, stirring with a whisk until well blended to form a slurry.
Combine 1 1/2 cups flour, sugar, and salt in a bowl, stirring with a whisk; cut in shortening with a pastry blender or 2 knives until mixture resembles coarse meal. Add slurry; toss with a fork until flour mixture is moist.
Gently press mixture into a 4-inch circle on heavy-duty plastic wrap, and cover with additional plastic wrap. Roll the dough, still covered, into an 18 x 12-inch rectangle; freeze 10 minutes or until plastic wrap can be easily removed. Remove 2 sheets plastic wrap, and place dough on a lightly floured surface; let stand 1 minute. Cut dough as directed according to the specific recipe. Chill dough until ready to use.