Make the Filling

1. Add pork to a large pot with onions. Cover with water. Cook on medium low heat 1½-2 hours. Stir occasionally to break up chunks of meat. Pork is done when there is no pink left and all of the meat is brown. Reserve about 1 cup of cooking liquid, and strain the rest
2. In a large bowl mix pork and onions with saltines. Add more salt and crackers to taste

Make the Crust

1. Mix flour and salt in a bowl. Use a fork or a dough cutter to cut the shortening into the flour. You want lots of small pieces, a little bit smaller than peas
2. Add milk and stir (use your hands) just until it starts to come together. Mixture should still be in pieces, with a little bit still dry. Turn out onto a floured board. Knead a few times, JUST until it's in one piece. Divide in 2 pieces. (At this point you can reserve the dough in the refrigerator, or roll it out right away)
3. Roll out dough and place in pie pan. Use a fork to dock the pie bottom all over. Add pork filling. Roll out top crust and cover pie. Use a little milk on the edge of pie to get the crust to stick together.  Pinch edges together. Cut vent holes in the top center of pie
4. Bake at 350º for 30-45 minutes, or until pie crust is light golden brown