In a large bowl add the flour and salt then mix until combined.
Add the cubed tenderflake to the bowl with flour, and then grate the cold butter over the flour mixture as well. Using a pastry cutter, or two knvies, to cut the lard/butter into the flour mixture until it resembles coarse crumbs.
In a 1 cup measuring cup add the egg, vinegar, and enough cold water to bring it to 1 cup measurement. Whisk witha fork to combine.
Slowly pour the egg mixture over the flour mixture, in 1/3 cup increments, until the dough will hold together. You may not need the entire liquid amount.
Once the dough has come together divide into three disks, wrap each one in plastic wrap and chill for atleast 30 minutes. For a double pie crust you will use two disks, for a single pie crust recipe just use 1.
Prepared pie dough will keep in the fridge a few days, or it can be frozen for a few months.