Bring a large pot of water to a boil. Put the pork bones in and boil for about 5 minutes. Discard the water and rinse the pork bones with cold water. Clean the pot and put about 12 cups of water into the pot and place the blanched pork bones in. Bring to a boil. Add in all the ingredients for stock and lower the heat to let it gently simmer for the next 1 1/2 to 2 hours
Making the wontons:
Mix all the ingredients for wonton in a large mixing bowl (except for the wonton skin) and let it marinate for at least 30 minutes
When ready to wrap, place one wonton skin on the palm of your hand and scoop about 1 tsp of filling or more into the center of the skin. Wet the edges of the skin with some water and gather all sides and pinch to seal on top. Feel free to make other shapes if you prefer. Continue with the remaining filling and wonton skins. Keep the wontons covered with plastic wrap or damp cloth to prevent drying
When ready to serve:
Bring the stock to a boil. Bring another medium-size pot of water with pinch of salt to a boil. When water is rolling boil, place the wontons in and let it cook for about 30 seconds. Scoop them out with slotted spoon and run them through cold water. Return them to the same pot of boiling water along with the chye sim and let them cook until they float to the top and the chye sim is cooked but slightly crunchy. The reason of doing this is to get rid of excess starch from the wonton skin and to let the skin nicely puckered up (to give you that nice "wrinkles). Remove the cooked wontons and place on large serving bowl or individual serving bowl
Ladle the boiling stock over the wontons (make sure the stock is rolling boil) and garnish with coriander leaves and spring onions. Serve with the dipping sauce on the side