Halve the red onion; dice one half and thinly slice the other and set aside.
Place the ground pork, breadcrumbs, egg, diced onion and garlic in a large bowl. Season with salt (in moderation) and pepper. Combine using your hands and form into balls.
Heat 1 tablespoon of oil in a large frying pan over a medium heat. Fry the meatballs for 15 minutes or until evenly browned and cooked through. Set aside and wipe out frying pan with a paper towel.
Heat the remaining oil in the frying pan over medium heat and sauté the bell peppers and sliced onion for 5 minutes, or until soft.
Meanwhile, mix the ketchup, soy sauce, vinegar, cornstarch and half a cup of water in a small bowl. Add this to the peppers and cook, stirring frequently, until the sauce thickens slightly. Add the pineapple and meatballs and warm through. Serve with rice.