In a food processor, put the flour, sugar, and salt in a bowl. Pulse several times to mix.
Scatter the chilled butter cubes over the dry ingredients and pulse the machine 5 or 6 times to cut in.
Fluff the mixture with a fork, lifting it from the bottom of the bowl. Scatter the chilled shortening cubes over the flour and pulse 5 or 6 times to cut in. Fluff the mixture again.
Drizzle half the water over the flour mixture and pulse 5 or 6 times. Fluff the mixture and sprinkle on the remaining water.
Pulse 5 or 6 times more, or until the dough begins to form clumps. Overall it will look like course crumbs. Dump the contents into a large bowl.
Knead the ball once or twice, then flatten the ball into a ¾" disk on a floured work surface. Wrap the disk in plastic and refrigerate for at least an hour or overnight before rolling.
Preheat oven to 400°.
On a sheet of lightly floured wax paper, roll the pastry into a 12" circle with a floured rolling pin.
Invert the pastry over a 9" standard pie pan, center, and peel off the paper. Tuck the pastry into the pan, without stretching it, and and sculpt the edge into an upstanding ridge.
Place in the freezer for 15 minutes.
Tear off a piece of aluminum foil about 16" long. Center the foil over your pie shell and then tuck the foil into your pie shell. It should fit the pastry crust like a second skin. Let the excess foil flare out like wings. Add pie weights to keep the crust from puffing up while baking.
At 400°, bake the pie shell on the center rack of the oven for 15 minutes. The slide the rack out and slowly lift out the foil with the weights.
Take a fork and prick the pastry all over the bottom, perhaps 7 or 8 times. As you twist the fork in, give it a little twist to enlarge the holes slightly. Don't worry about the sides unless you see them puff up, then open the over and stick a fork in to deflate.
Lower the oven temperature to 375° and continue to bake the pie shell for 10-12 minutes. Check to make sure it isn't puffing up and is lightly browned. Turn the oven off.
Whisk an egg white until frothy then with a brush, paint over the holes to keep the filling from leaking out. Put the pie shell back into the hot oven, to bake the egg white to a hard finish, about 2 minutes. Remove pie shell from oven, and put it on a wire rack to cool.