1. In a medium saucepan, heat the oil (1 tbsp) until warmed and add garlic, stir until fragrant. Add onion and celery, continue stirring until they becomes wilted. Add butter and cook. Let it cool.
2. In a medium bowl, add minced beef, scallion, lukewarm onion mixture and the seasoning "A". Mix to combine evenly. Set aside.
3. Dampen your hands with clean water and make the rice into about 3cm balls.
4. Cover each rice ball with some of minced beef mixture and make it into the ball shape.
5. Cook the meat-rice balls on all sides until no longer pink. Transfer the meatballs on the plate.
6. In a small bowl, mix all the sauce ingredients together. Pour the sauce mixture into the fry-pan where you cooked the meatballs. Place the meatballs onto the sauce and reduce the heat to low. Cover and cook for about 15 mins. Dress the meatballs generously with the sauce.