1. In a bowl, mix unbleached or regular all-purpose flour and salt. Add 3 tablespoons cold butter or margarine, cut into chunks, and 3 tablespoons cold solid shortening, cut into chunks (or omit butter and use 6 tablespoons shortening). With a pastry blender or your fingers, cut in the fats or rub with your fingers until mixture forms pea-size crumbs.
2. Sprinkle 3 tablespoons cold water over crumbs and mix with your hands until evenly moistened. Gently squeeze about 1/4 cup of the dough into a ball; if it won't hold together, crumble lump back into bowl, sprinkle with 1 more tablespoon water, and mix again until evenly moistened.
3. With lightly floured hands, form dough into a ball. Dust ball lightly with flour; flatten into a round about 3/4 inch thick, pressing edges to make smooth.
4. On a lightly floured surface, with a lightly floured rolling pin, roll dough firmly but gently in short strokes from the center outward to form a round 1/8 inch thick and about 12 inches wide; lift and turn dough occasionally, dusting underneath with more flour. If edges split while rolling, press them back toward the center to make smooth.
5. Fold dough round in half, lift gently without stretching, and lay folded edge across the center of a 9-inch pie pan. Unfold and ease dough into pan. Trim edge evenly 1 inch beyond pan rim; reserve scraps for other uses or discard. Fold edge under itself flush with rim; flute decoratively. Cover crust and chill until ready to use.