In a big pot, add 4 cups water and bring to a boil.
Add beef shank, onions and whole peppercorns to the pot.
Simmer for 3 hours or more until meat is very tender.
Add about 4 cups of water while simmering.
Add corn and simmer for another 15 minutes.
Add green finger chilies.
Add fish sauce, cabbage and bok choy. Cook for 5 minutes.
Serve and enjoy.
inspired by Yummy.