In a large pot, combine 5 cups of water with the shrimp paste, galangal, ginger and garlic. Bring to a boil.
Add fish and simmer for 4 minutes. Remove fish to a bowl or plate. Remove flesh from the bones. Set flesh aside and return fish bones to the water. Bring to a boil and simmer for 10 minutes. Drain bones and discard. Add water to broth to make 4 1/2 cups.
Return broth with additional water to the pot and bring to the boil. Add turmeric, banana stem, fish sauce, tamarind concentrate, pepper, chile paste and cilantro. Add fish and simmer for 5 minutes.
Cook vermicelli according to package instructions. Add shallot oil, soybean flour and fish sauce to the noodles. Toss well.
For each serving, place a portion of vermicelli in the bottom of a bowl. Ladle some of the soup over it. Add a generous handful of the cilantro and stir into the soup.
Serve with fish sauce and chile paste for each person to flavor more as they desire.