The secret to an irresistibly flaky crust is simple: Don't overwork the dough.
Whisk 1 1/4 cups all-purpose flour, 1 teaspoon sugar and 1/2 teaspoon salt in a bowl. Cut 1/4 cup each cold unsalted butter and shortening into pieces.
With a pastry blender, cut shortening and butter into flour mixture. (Or rub with your fingertips until consistency of coarse meal.) Mix in 3 tablespoons cold water with a fork. Gather into a ball; flatten into a disk. Wrap in plastic and chill for 30 minutes.
Heat oven to 425°. On a floured surface, roll pastry to a 13-inch circle, coating with flour as needed. Run a spatula under crust if dough sticks. Roll pastry onto rolling pin and unroll into a 9-inch pie plate.
Fold crust under to form a stand-up edge. Pinch two fingers together against inside of crust and with opposite index finger press against outside edge to flute. Continue around crust.
Chill until oven is heated. Prick crust with a fork and line with foil. Fill foil with pie weights or dry beans. Bake at 425° for 15 minutes. Remove foil and weights. Bake 8 to 10 minutes more until golden. Let cool completely.