Sift the flour and salt into a large bowl. Using your fingertips, work the butter and shortening into the flour until the mixture resembles small peas. Work the ice water into the mixture with your fingers until the dough just comes together; be careful not to overmix. Form the dough into a disk, wrap tightly in plastic wrap, and refrigerate for at least 30 minutes before rolling out.
Makes one 9- or 10-inch piecrust