Add the flour and shortening to a medium size mixing bowl.
Using a pastry blender, cut the shortening into the flour mixture until it resembles course crumbs and there are no large clumps of shortening remaining.
Add the egg, water, vinegar, salt, and baking powder and stir until incorporated.
Turn out the dough onto a flat, floured surface.
Form the dough into a rectangular brick and divide into 3 equal portions.
Wrap each portion in plastic wrap and refrigerate for 30 minutes or freeze for 15 minutes.
Place one of the chilled dough portions onto a floured, flat surface.
Roll out the crust with a flour dusted rolling pin until it is about 1" wider then the pie plate.
Using a metal spatula or other thin, flat implement dipped into flour, flip half of the crust over to make moving into the pie plate easier. See above photo.
Fill crust with desired filling.
For a single crust, use 3 finger tips to create a scalloped edge by pinching and tucking. See above photo.
For a lattice top crust, roll out a second crust following the above steps.
Cut the crust into 10 similar width strips.
Create the lattice by laying 5 strips equidistant apart vertically.
Lay the remaining 5 strips equidistant apart horizontally, lifting the vertical strips as needed to create the under and over lattice effect. See above photos.