Trim off any excess fat from the oxtail and blanch in boiling water for 5-6 minutes. Drain and set aside. Bring chicken stock or water in a deep pot to a boil. Put in ingredients (A) and simmer for 5-10 minutes. Add oxtail, garlic, onions, ginger, galangal, leek, celery and coriander roots. Bring to a boil again then reduce the heat and simmer the soup over a gentle low heat for an hour. Add carrot and radish and continue to simmer for another 30 minutes or until meat is tender. Adjust seasoning to taste and dish out to serve immediately with the garnishing.