I can remember as a little girl watching my Gram cook, she never measured and I learned to watch "the Look" of the receipe. This is a tried and true best pie crust receipe, always comes out nice and flakey!
cut as much of the flour into the butter until it is small little crumbles of flour dough
add the egg yolk and the tablespoon of vinegar until the dough is little marble size balls of dough.
add the ice cold water slowly until the dough forms a single ball of dough.
Let refrigerate until ready to roll, use the remaining flour and roll thin. Fold over and put into pie plate. If useing this for a single layer pie (ie, lemon, breakfast, or pudding type pie) prick bottom of and bake for five minutes at 450 degrees. If using for double layer pie it is not necessary to bake prior.