Marinate oxtails in soy sauce, oyster sauce, and liquor for one hour.

Cook covered over medium heat for 30 minutes to draw out juices.

Uncover, bring to a boil, and brown the meat, evaporating the liquid.

Add garlic, bay leaves, oregano, chopped onion, and 1/4 cup beef broth. Deglaze the pan.

Add remaining beef broth, cover, and simmer gently for about 3 hours, until meat is tender.

Remove from heat and strain broth into a saucepan or bowl.

Discard onion and herbs and set meat aside.

Cool meat, remove from bones, cut into bite-sized pieces, and return to broth.

Refrigerate several hours or overnight.

Skim off and discard fat.

Bring broth to a boil.

Add celery, carrot, and remaining chopped onions. Reduce heat, cover, and simmer until vegetables are tender (about 20 minutes).