1. Spray slow cooker lightly with cooking spray. Put sliced onions on the bottom. Rinse pork loin and pat lightly with paper towels. Coat it with a layer of Lawry's Seasoning Salt and some pepper. Place on top of onions.
2. In a medium sized bowl, mix 1/2 bottle of barbecue sauce and a can of diet soda. Pour the fizzy concoction on top of seasoned pork loin in crock pot.
3. Cover the crock pot and cook on LOW for about 7-8 hours, or until meat is fork tender. When the meat is tender enough, carefully take the pork out of the slow cooker and place on a plate and shred the meat up using two forks. Place meat back inside crock pot, stirring to combine, and let cook for another 30 minutes.
4. Serve on buns and ENJOY!!