Trim any visible fat from pork roast. In a small bowl combine cinnamon, pepper, sugar, onion, and garlic; add soy sauce to make a paste. Rub mixture into pork loin. Put in a sealable plastic bag and refrigerate 3 hours to overnight.
Oven: Preheat oven to 325°F (160°C). Place pork in a shallow foil-lined baking dish. Roast pork for about 50 minutes or until meat thermometer registers an internal temperature of 140°F. Cover loosely with foil and allow to rest for 5 - 10 minutes (internal temperature will rise to about 145°F) before cutting into thin slices.
BBQ: Grill pork over medium-low indirect fire 1 ¼ to 1 ½ hours (about 18 - 20 minutes per pound) or until the internal temperature is 140°F. Cover loosely with foil and allow to rest for 5 - 10 minutes (internal temperature will rise to about 145°F) before cutting into thin slices.
Serve with unsweetened apple sauce, mashed potatoes, and your favorite green or orange vegetables.
