Mix together the ingredients for the Dry Rub in a small bowl.
Trim off any large, hard fat pieces from the pork roast. Rub the pork shoulder with the dry rub on all sides. Place into the slow cooker.
Stir together the apple cider vinegar, worcestshire sauce, and liquid smoke in a small bowl, then pour over the pork roast in the slow cooker.
Cook on Low heat for 8-10 hours, or until tender.
Carefully remove the pork to a large baking sheet. Keeping it as intact as possible.
Broil on high heat in the oven for 5 minutes to get the crispy pieces of pork.
Remove from the oven and allow to cool briefly. Using two forks, shred the meat.
Serve warm on hamburger buns.
