Mix flour, sugar and salt in a large mixing bowl. With a pastry blender, or using a food processor, cut in the shortening and butter until it resembles coarse crumbs.
Mix in the iced water, one tablespoon at a time, until dough forms a ball. If dough doesn't come together or looks crumbly, gradually add more ice water, 1 teaspoon at a time, until it does. Take the dough out of the food processor (if using) and knead gently with your hands a few times. It should feel pliable and smooth. If not, add a little more water and knead in. Do not over process the dough.
Divide dough into two balls and flatten slightly into discs. Wrap well in plastic wrap and chill in the refrigerator for at least 30 minutes before rolling.
Using a well-floured surface and a rolling pin, roll each pastry disc from the center to the edges.
Roll each pastry into a circle that is several inches larger than a 9-inch pie plate.
Place gently in pie plate and trim overhang. Fill pie and add top crust as recipe directs.
Preheat oven to 400 degrees (F).
Drain the cherries and reserve the juice from only one can.
In a saucepan, stir the cherry juice into the combined mixture of the cornstarch and sugar. Cook over medium heat, stirring constantly until thickened, but not gluey.
Remove from heat. Stir in vanilla extract, then gently stir in cherries.
Pour filling into pastry lined pie pan. Dot with butter or margarine.
Place second crust on top and gently seal by making a decorative edge with your fingers or the tines of a fork. Vent the pie by slashing the top crust several times. Or do as Max and Callie do, and use a shaped pie crust cutter to make decorative vents in the crust (such as a cherry shape). Place cut-outs on the crust and gently seal for additional decoration.
Bake 30 - 40 minutes or until crust browns and filling begins to bubble though the vents. Make sure it's bubbling or the filling will be too thin or "runny" once it cools.
If the edges of the pie are browning too quickly, cover with aluminum foil or "pie crust protectors" (found at kitchen stores) for the last 15 minutes of baking.
Cool pie several hours to allow filling to thicken before slicing.
* You can substitute well-chilled vodka for the water. This creates a super flaky crust and cuts down on the worry of over-handling the dough.
You can make the dough a couple of days in advance and store in the refrigerator until ready to use.