Place the pork ribs in a large pot and add just enough water to submerge them. Bring to a boil over high heat. Once scum has formed, turn off the heat, discard the water, and give the pork ribs and pot a quick rinse.

Return the pork ribs to the pot and add about 8 cups of water, along with the sliced onion, peppercorn, and fish sauce. Bring to a boil over high heat. Once boiling, cover and turn the heat to low. Let it simmer until the meat is fork-tender.

While the pork is simmering, prepare the vegetables and bananas. Wash and peel the potatoes, then cut them into quarters. Cut off the ends of the bananas, wash thoroughly, and cut each into 3 pieces diagonally (unpeeled). Soak both potatoes and saba bananas in water until ready to use.

Cut off the stem of the pechay, wash the leaves thoroughly. Remove the ends of the beans and cut into about 3-inch lengths. Remove the root part of the onion leek and cut it into 2-inch pieces.

Add the green bananas and cook for 5 minutes, then add the potatoes and cook for another 5 minutes. Finally, add the green beans and cook for another 5 minutes or until the potatoes are cooked.

Season with salt and pepper to taste, then add the green onions and pechay. Cover the pot and let it simmer for a minute before turning off the heat.

Serve in a large soup pot or individual bowls.