Mix the flour, salt and baking powder in a large bowl.  Add the fats, and using a hand pastry blender, mix the flours and fats together.  Whisk the egg in a cup, add the vinegar and enough water to fill the cup.  Pour onto the flour mixture and blend well.  I use my fingers, but use a very light touch.  You don't want to over blend or work the dough too much.  Otherwise the pie crust will be tough.

Shape the pastry dough into 4 evenly shaped balls, wrap them in plastic wrap and place in the refrigerator for at least 30 minutes.

Using a pastry mat, roll out the dough evenly and until it is the right size to fit your plate.

Wrap the dough around the rolling pin and rest the pin and pastry dough in the middle of the pie plate, in order to centre the pie crust.

Unroll the pie crust, gently pushing it into a well greased pie plate,

Crimp the edges using your knuckles of the index and middle finger on your right hand, and pushing with your third finger on your left. Or vice verse if you are left handed.

Prick the bottom crust a few times with a fork.   

Wrap the pie crust in plastic wrap and chill for 30 minutes before baking,