For the meat stock, rinse the bones and slowly bring them to the boil in a large pot with about 3 litres of water and simmer at low heat for 3-4 hours. Skim off the resulting foam from time to time. Pour broth through a fine sieve
For the soup, roast anise, cinnamon and cardamom in a large pot while stirring until the spices start to smell. Add 2 litres of meat stock and bring to the boil. Season with salt. Simmer for about 10 minutes. Pour soup through a fine sieve
Soak the pasta in cold water for about 20 minutes. Briefly pour boiling water over the sprouts and let them drain. Clean, wash and chop the spring onions. Clean, wash and cut the chillies into thin rings. Wash lime hot, grate dry and cut into eighths. Wash the herbs, shake dry and pluck off the leaves
Bring the soup back to the boil. Dab fillet dry and cut into thin slices. Arrange drained noodles, sprouts, spring onions and fillet in soup bowls. Pour boiling broth over them. Add chili, lime and herbs and season the soup to taste