Adapted from SalllysBakingAddiction.com with a couple of minor change. I added a splash of vinegar. About 1 teaspoon. I used butter flavored vegetable shortening.
In a medium size (chilled if you like) bowl, mix flour and salt together
Add COLD cubed butter and COLD shortening to flour mixture. Using two forks or a pastry cutter, combine all ingredients together until mixture has texture of a coarse meal. Do not over work the dough. You want it to be lumpy.
Measure the tsp of vinegar into your measuring cup and then add the ice water to measure a total of 1/2 cup.
Add most, but not all of the water to the flour mixture. Stir to combine using a wooden spoon or rubber spatula. Mix until the dough has started to clump together. Add a bit more water if needed. Depending on your environment you may need to add up to another 1/4 cup. I added exactly 1/2 cup and the dough was perfect. It's ok if its a bit crumbly. You want it to just hold together.
Form the dough into 2 round disks. Wrap them well in plastic wrap. Allow the dough to rest in the refrigerator and hour or two before rolling it out.
The dough will keep in the refrigerator for up to 5 days and up to 3 months in the freezer.