Mix soy sauce, (rum optional) and Tex's Tropical Pork Seasoning in a small bowl. Use a sharp knife to make criss-cross cuts on the surface of the pork. Rub seasoning into the cuts and all over joint. Leave to marinate for 2 hours or overnight in the fridge.
Place in a preheated oven at 180?C/350?F/Gas Mark 4 and roast for approximately 90 minutes or until cooked.
When roasting, cover pork with foil and roast for first hour then remove foil, turn over and baste with pan juices and continue to roast till juices run clear when pierced.