Mussels, an economical choice, give essential flavour to this soup. The proportions of the fish and prawns are flexible.
- Discard any broken mussels and those with open shells. Rinse, pull off any beards, and if the are barnacles, scrape them off with a knife under cold running water. Put the mussels in a large heavy based sauce pan. cover tightly and cook over a high heat for about 4 minutes, or until the mussels open, shaking the pan occasionally. remove the mussels from their shells, adding any juices to the cooking liquid. strain this through a muslin lined sieve and reserve.
- Put the flour in a mixing bowl and very slowly whisk in enough of the stock to make a thick paste. Whisk in a little more stock to make a smooth liquid.
- Melt the butter in heavy based saucepan over a medium-low heat. Add the onion, cover and cook for about 5 minutes, stirring frequently, until it softens.
- Add the remaining fish stock and bring to the boil. slowly whisk in the flour mixture until well combined and bring back to the boil, whisking constantly. Add the mussel cooking liquid. Season with a little salt, if needed, and pepper. Reduce the heat and simmer, partially covered for 15mins.
- Add the fish and mussels and continue simmering, stirring occasionally, for about 5 mins, or until the fish is cooked and begins to flake.
- Stir in the prawns and cream. Taste and adjust the seasoning. Simmer for a few minutes to heat through. Ladle into warm bowls, sprinkle with dill and serve.