Cut one onion in slices place at bottom of crockpot. Season the pork with salt, pepper, garlic, little bit of ground mustard and add a few cloves along the crease of the pork. Place pork in crockpot ontop of the onions and place the rest of the onion slices on top of the pork.
Add ginger ale or root beer. Cook on high for 5-6 hours or low for 9-11 hours. Depends on the size of the pork and how long you have to cook it. I recommend slow/low- Start it first thing in the morning and its ready for dinner!
You can turn the pork over for a more even cook halfway through. Try not to open the lid to much despite how AMAZING it will smell.