In a large bowl, combine the sugar, salt and flour. Using two knives or a pastry blender, cut the butter and shortening into the flour until the mixture resembles course crumbs.

Stir in the vinegar and then the water (1 tablespoon at a time), until the dough begins to form.

Press the dough together and shape into a disk.

Wrap the dough with plastic wrap and refrigerate for at least 1 hour.

On a floured surface, roll out the dough to a 12-13-inch circle; fit into a 9-inch pie pan, pressing to fit and crimping the edges to form a rim.

Freeze for about 20 minutes.

Prick the bottom of the dough with a fork.