In a large pot, combine the beef shanks and 10 cups of water. Bring to a boil over medium heat. Skim off any scum that rises to the surface to keep the broth clear.
Once the scum is removed, add the quartered onion and whole black pepper. Lower the heat and let it simmer for about 1.5 to 2 hours, or until the beef is tender. If you have a pressure cooker, you can cook the beef for 30-40 minutes to save time.
Once the beef is tender, add the fish sauce and stir.
Add the corn pieces and quartered potatoes to the pot. Simmer for about 10-15 minutes, or until the potatoes are tender.
Add the saba bananas and continue simmering for another 5-7 minutes until the bananas are cooked through.
Finally, add the cabbage quarters and pechay. Simmer for another 2-3 minutes, just until the vegetables are tender but still crisp.
Taste the broth and season with salt as needed.
Serve hot with steamed rice and enjoy!