Mix the mince with the onion, rolled oats, Worcestershire sauce, egg, paprika, tomato sauce and 1 tsp salt.
Heat oil in frying pan, shape mince mixture into meatballs and fry, carefully browning on all sides. Cook in batches, and transfer to a casserole dish when browned.
When all the mince mixture is cooked into meatballs add the sweet and sour sauce along with the water to the casserole dish.