(3/4 stick) unsalted butter, chilled and cut into 1/2 inch pieces
solid vegetable shortening, chilled and cut into 1/2 inch pieces
(or more) ice water
Mix flour, sugar and salt in processor.
Add butter and shortening. Using on/off turns, process until mixture resembles coarse meal.
Drizzle 3 tablespoons ice water over mixture. Process just until moist clumps form, adding more ice water by teaspoonfuls if dough is dry.
Gather dough into ball; flatten into disk. Wrap in plastic; chill until dough is firm enough to roll out, about 30 minutes.
Roll out dough on lightly floured work surface to 12-inch round. Transfer dough to 9" diameter glass pie dish. Fold overhang under. Crimp edges decoratively. (Can be prepared 2 days ahead. Cover and refrigerate.)