You can get the beef shank from a nilagang bulalo dish but if you don't have any you can boil the beef shank until the meat is tender. You can use a pressure cooker to speed up the cooking. (Before boiling the beef shank, put 1 pc peeled onion, sliced in half.)
Remove the cooked bulalo from the soup stock and get the meat with the bone shank.
In a deep pan or wok, heat the cooking oil and saute garlic and onion.
Then follow the beef shank or bulalo and stir fry with the sauteed garlic and onion.
Allow the beef to fry a little bit for 3 minutes. Then pour the soup stock and pepper.
Simmer for 5 minutes then add the oyster sauce, vinegar and sugar.
When the sauce becomes thick, remove from fire and serve hot.