In a very large bowl, combine 3 3/4 cups all-purpose flour, 1 tablespoon sugar, 1/2 to 1 tablespoon salt, and 1/2 teaspoon baking powder. With a pastry blender cut in 1 3/4 cups cold unsalted butter leaving chunks the size of peas. Combine 2/3 cup ice-cold water, 2 tablespoons of sour cream and 1 teaspoon vinegar. Add liquid all at once to the four mixture. Quickly stir to distribute; do not overmix. The dough should be slightly crumbly. Let rest in the refrigerator for at least 2 hours or overnight. The finished dough should break, not stretch. Divide into three portions; shape into disks. Use at once or wrap and refrigerate up to 3 days. Or freeze up to 1 month. Thaw overnight in the refrigerator if frozen.
Makes 3 single-crust pastries.
Better Homes & Gardens, November 2010