Drain pineapple, reserving 1/4 cup juice. Set aside 1 cup of pineapple (save remaining pineapple for another use). Place the pork on a rack in a shallow roasting pan. Combine 2 tablespoons brown sugar, mustard, paprika and ginger. Spread half over the pork.
Bake, uncovered at 450° for 15 minutes. Spread with remaining brown sugar mixture. Bake 15-20 minutes longer or until a meat thermometer reads 160°
Meanwhile, for salsa, in a small bowl, combine the red pepper, onions, pepper flakes if desired, remaining brown sugar, reserved pineapple and juice. Let pork stand for 5 minutes before slicing. Serve with salsa. Yield: 4 servings.