Place the hock in a large saucepan, cover with cold water and bring to the boil. When foam appears on the surface, drain the hock, discarding the water. Wipe the saucepan clean before adding the hock and covering with 4-5L cold water. Add the onion, cinnamon, star anise, garlic, ginger and kombu. Simmer on low heat for 4-5 hours, or until the bone can easily be removed.
Strain the broth into another saucepan and keep warm over low heat. When the pork is cool enough to handle, remove the bones and gently pull apart the meat. The fat and gelatinous skin can be finely sliced and stirred through the pork.
Cook your chosen greens in the simmering pork broth while you prepare the noodles according to the instructions on the pack.
To serve, place the noodles in a bowl. Top with the pork and greens before ladeling over the hot broth. Season with a little tamari or fish sauce.