1In a small bowl, stir together garlic powder, mrs dash, and pepper. Trim fat from meat. Sprinkle pepper mixture evenly over meat; rub in with your fingers. If necessary, cut meat to fit into a slow cooker.
2Place onion in the bottom of slow cooker. Add meat. Pour the water and vinegar over meat.
3Cover and cook on low-heat setting for 8 to 10 hours or on high-heat setting for 4 to 5 hours. Remove meat and onions from cooker to a cutting board; discard all but 1/2 cup of cooking liquid. Using two forks, pull meat apart into shreds. Cut up onions and place on shredded pork.
4In small bowl, combine juices with BBQ sauce. Drizzle on shredded pork and stir to lightly coat.
5Place meat mixture on bottoms of buns. Top with apple slaw mixture; and tops of buns.