Pre-marinade the pork ribs with Shaoshing rice wine and soy sauce. Let that rest for half an hour at room temperature.
In the meantime prepare the vegetables and set side on a large plate. For the pickled mustard greens, trim the bottom of and then separate each of the leaves.
In a large stockpot or pot on medium high heat, add cooking oil and let it heat up. Once oil is hot enough, place the pork ribs into the pot to sear the meat. Sear the meats on all side. When the meat has seared add the onions and half amount of spring onion stalks. Using a wooden spoon, stir to coat the onions and spring onions with the rich flavours at the bottom of the pot.
Add garlic, ginger and stir for about a minute, then fresh chillis, chill flakes and mix. Now add the carrots into the pot and stir for 30 seconds.
Add the bottoms of the pickled mustard greens, green part and the remaining spring onion stalks, daikon (optional) and stir together. Into the pot add liquid from the mustard greens and give it another stir. Pour in hot boiling water and fill the pot to the top, until the meat and vegetables are fully covered. Cover with a lid.
Bring to a boil and skim scum off the impurities coming from the meat. This will give the soup a more refined taste. Turn the heat to medium low and cover again. Let it simmer for 20 to 30 minutes to ensure all of the rich flavours come together. Simmer until the pork rib become tender and daikon is soft.
Place the sweet corn on the outer edges of the pot, let the soup simmer for another 20 minutes and cover. Then add the watercress (optional) using a wooden spoon to push it into the soup.
Finally add the button mushrooms, cover again and let it simmer for a further 5 minutes.
In a serving bowl, add one or two pieces of pork rib, sweet corn and mustard greens. Then using ladle scoop the other vegetables and the soup into the bowl. Serve and eat immediately while hot. This can also be served with a bowl of rice on the side.
