In a mixing bowl, combine the flour, salt and Crisco. Cut Crisco into the flour with a pastry blender or a fork until mixture is crumbly.
In a small dish, add yolk, vinegar, & water; blend well with a fork. Add liquid to flour mixture and blend well with a fork until dough is thoroughly incorporated then use your hands to work it together to form a ball. Divide the dough in half to make 2 balls.
Place one ball of dough between 2 sheets of waxed paper and roll it out with a rolling pin; rolling it a little larger than the size of your pie pan. Remove top piece of waxed paper and then gently flip over the dough onto your pie pan. Remove waxed paper and gently shape the dough into the pie pan. Trim excess dough off. Repeat with second half of dough. Bake according to pie recipes.
Note: You can get 3 pie crusts out of this depending on how thin you roll your crust out. I personally like a thicker crust. And -- If there are any scraps of crust left over, you can roll it out and put them on a cookie sheet; sprinkle with sugar and bake untill golden. A very tasty treat.