To make the cranberry sauce put all ingredients in a small saucepan over medium heat. Mix well. At first boil, reduce heat to low, cover and cook for 20 minutes.
Season the pork with salt, black pepper and cayenne pepper to taste. Be generous.
Place the pork in the slow cooker. Add onion and garlic. Cover the pork with cranberry sauce and then add the beer. Cook for 8 hours on low or 4 hours on high. The pork should be so tender that meat falls apart easily. Using two forks pull apart the pork, removing excess fat.
Heat oven to 450 ° F. Line one baking sheet with foil and spray with cooking oil.
Place pork in sheet, with juices, and bake for 15-20 minutes, or until most of the liquid has caramelized and the pork looks golden. Remove from the oven.
Add a generous portion of pork on a bun with some coleslaw, if desired.
Serve immediately and enjoy!