Combine mince,egg, one of the onions, 2 tablespoons curry paste 3 tablespoons of coriander and 1 clove garlic. Form mixture into small meatballs.
Heat 1 tablespoon of oil in non stick frying pan and cook balls in batches until golden (do not need to be cooked through at this stage) Repeat until all balls are cooked till golden, remove from pan and set aside. Cook remaining onion and garlic till softened, add remaining curry paste and cook for 1 minute then add one cup of water and diced tomatoes. Let mixture simmer for 5 minutes before placing meatballs and any juices to the sauce, and gently stir.
Simmer until meatballs are cooked through.
Serve with rice or mashed potatoes sprinkled with remaining coriander.