Ingredients

Step by step

1. Take the heads off the fish and remove the fillets (or ask your fishmonger to do this for you). Trim the fillets, taking out any small bones and cut each fillet in half, cover and put in the fridge. Put all the bones, carcass and heads into a large pan and cover with 1.2 litres of cold water; add the salt. Slowly bring to the boil, then turn the heat down and simmer for 30 minutes. Turn off the heat and set aside for 20 minutes. Sit a sieve over a bowl, strain and discard any bits.
2. Wash the large pan and add the oil, heat gently, then add the shallots, garlic, celery, chillies, oregano or thyme, coriander stalks and season well with black pepper. Cook gently for 10 minutes without colouring. Then add the tomatoes. Take 100ml of the strained stock and put it in a lidded pan big enough to take the mussels and put this to one side. Add the rest of the stock to the vegetable pan and, bring to the boil and simmer gently for about 20 minutes.
3. Put the reserved stock on to boil and add the mussels, cover with a lid and cook for about 4 minutes or until the mussels have all opened (discard any that remain closed). Strain the mussels through the sieve over the bowl, then put them in a clean bowl and cover until serving. When the mussel liquor has settled, carefully pour into the pan of stock mixture – leaving any grit behind in the bowl. When cooled slightly, process in a liquidiser and pass through a sieve set over the pan, pushing all the solids through with the back of a ladle or spoon.
   Tip

   You can make your own fish stock for this soup – but if you're short of time, buy prepared skinless, boneless sea bream and use 1 litre of ready-made fresh fish stock instead.
4. When ready to serve, heat the soup and add the crab and/or prawns, cook for 3 minutes. Add the fish pieces and cook the soup for a further 3 minutes, then add the mussels for the final minute. To finish, stir in the coriander sprigs before serving.