On medium heat, Mam Ca Linh and Mam Ca Sac with 1qt of water for 30 minutes until all the meat fallen of the bones. If you use cream style of these fermented fish, you should do this step too to make sure the soup is clean of lumps. After that, strain the liquid to a fine mesh. Combine this with 3qt of water in a big pot, lemongrass, rhizome (mashed) and Thai chilies. Bring the mixture to boil then simmer for 15 minutes.
Cut pork belly in to small pieces, saute them in a medium pan with 10oz of lemongrass until the meat is half-cooked. Add pork in soup pot and simmer for another 30 minutes.
Saute eggplants with another 10oz of chopped lemongrass for 5 minutes. Add these in the pot and cook for 15 minute on medium heat. Lower the heat to the lowest level while preparing seafood ingredients.
In a medium pot, boil vermicelli and seafood then set aside. Serve soup with veggie on the side