1. Clean and chop the pork bone into 4 cm pieces.
2. Put 800 ml water into a saucepan, add the stock cube, salt and sugar and boil.
3. When the water is boiling, pound the garlic with black peppercorn and add to the pan. Add the pork bone pieces and boil gently for 40 minutes.
4. Mix the sticky rice flour and cassava starch together, add just enough water to form a paste and mix it together well.
5. Pinch off small pieces of the flour paste, roll them between the palms of your hands to make worms, and drop them into the boiling soup.
6. Repeat this until all of the flour paste has been used up, then continue simmering the soup slowly for 20-30 more minutes.
7. Serve, garnished with coriander leaves, and lots of fresh grated pepper.