Sift the flour, sugar, and salt into a large mixing bowl. Add the butter pieces and shortening, and work with your fingertips until it comes together and forms small pea shapes. Work the ice water into the dough until it just comes together, being careful not to overmix. Form the crust into a disk shape, wrap tightly in plastic wrap, and place in the refrigerator to rest for at least 30 minutes.
Preheat the oven to 375 degrees F.
Place the dough on a lightly floured surface and roll into an 11-inch circle. Transfer to a 9-inch tart pan with a removable bottom, trim any excess dough, and refrigerate for 30 minutes. Remove from the refrigerator and cover the bottom with a sheet of parchment paper and layer of pie weights or uncooked beans. Bake for 10 minutes. Remove the parchment and beans, and cook until the crust has just colored and is set, about 10 minutes.
Remove from the oven and cool on a wire rack.
Yield: 1 (9-inch) tart crust