Fill a large pot halfway with water and bring to a boil.
Place the beef shank in the pot, followed by the onion and whole pepper corn, and cook for 1.5 hours (30 minutes if using a pressure cooker) or until the meat is tender.
Cook for another 10 minutes after adding the corn.
Combine the fish sauce, cabbage, pechay, and green onion in a mixing bowl (onion leeks)