Grandma's Pie Crust

My grandma swears by this recipe for pie crust. It turns out well everytime. She says that she often will make more than she needs and then wrap it well in saran wrap and freeze it. She then puts it in the fridge to thaw the day before she needs it. She claims that it rolls out better after it's been frozen than it does when it is fresh. I have yet to try that little trick though. :)

3 cups flour
1 teaspoon salt
1 cup shortening
1 egg
5 Tablespoons cold water
1 Tablespoon vinegar

Mix flour and shortening together until mixture looks like cornmeal. Then add egg, vinegar, and water slowly until you get a nice ball of dough formed. Freeze overnight. Thaw in fridge until workable.