Heat oil in a large skillet. Combine the beef, garlic, 1 tsp salt and ¼ tsp pepper together and shape into 36 small meatballs.
Beat the eggs, flour, 1 tsp salt, ¼ tsp pepper together to make a thin batter. Dip the meatballs in the batter with fingers. Shake off excess and drop into the hot oil. Cook slowly to brown on all sides. Lift out the meatballs as they brown.
Discard all but 1 tbsp of oil left in the pan when all the meat balls are browned. Add the chicken stock, green peppers and pineapple chunks to the pan. Cover and simmer for 5 minutes. Return meatballs to the pan and simmer 3 more minutes (green peppers should still be slightly crisp).
Mix cornstarch, sugar, pineapple juice, vinegar and soy sauce together until smooth. Add gradually to the pan, stirring constantly. Continue cooking and stirring until thickened. Add tomato pieces just before serving and serve over rice.