Pre-heat the oven to 180 deg C (350 deg F) – Spray a 20 x 30cm ( 8 x 12 inch ) oven dish with cooking spray.
In a large mixing bowl, combine the Beef, Bread Crumbs, Egg, Water, half of the chopped Onion, (half of the Green Bell Pepper, if using) half the Salt and half the Black Pepper – mix well and form into balls – place in a single layer on the prepared oven dish.
In a small bowl, mix together the remaining Onion, Salt, and Pepper – add the Garlic, Tomato Sauce, Coca-Cola, Worcestershire Sauce and the Green Bell Pepper – pour over the meatballs.
Bake 50 – 60 minutes (turning twice) until sauce is bubbly and the meatballs are fully cooked.