Heat rum over medium heat in a saucepan. Warm for 1-2 minutes to burn off the alcohol. Add ginger, orange juice, sugar, salt, pepper, and cranberries to the pan. Simmer for 10-15 minutes until the cranberries split open. If you want a smoother thicker sauce puree the mixture.
Cut quarter inch slices into the cap of the pork belly about an inch apart. Coat the top of the belly with the pork rub. Wrap and refrigerate overnight. Remove from refrigerator. Brush off excess rub and allow belly to rest for an hour at room temperature.
Heat olive oil in a rondeau over medium heat. Place belly fat cap down and slowly brown and render excess fat from belly. Once skin is crispy. Remove from pan and transfer to a rack in a roasting pan.
Heat oven to 350° and cook belly for 2-2 ½ hours until tender.
Rest for 30 minutes before carving then serve with a side of cranberry orange glace.