The fish I bought yesterday is destined to become fish soup. Fish soup needs fish stock, and that is what you see pictured above.
Fish stock is so much quicker to make than a meat stock. All you need is some aromatic vegetables, herbs, some fish bones and to remember not to simmer it for more than twenty minutes. A too-long simmered fish stock will be bitter.
The choice of fish is only governed by what you know about fisheries and their methods and the oiliness of the fish. Choose a white non-oily fish, and you may as well choose one that isn't too expensive. I had bought a whole tarakihi to provide the bones of the stock. Sorry. You can add some prawn shells if you have some from using the prawn meat in a different recipe. Use any aromatic vegetables you like - carrots, onions, fennel or mushrooms. The herbs could be thyme, fennel, bay or parsley.
I make fish stock like this :
500g fish bones, including the head and skin. This was one tarakihi minus its fillets.
1/2 a small carrot, chopped
1/2 a medium onion, chopped
1/2 a medium fennel bulb, chopped
a handful of fennel leaves and stalks
a sprig of thyme
Put all the ingredients in a large pot and pour over one litre of cold water. Bring to the boil then reduce the heat to low and simmer gently for twenty minutes. Strain though a very fine sieve, through muslin if you like, discarding all solids. Leave to cool then refrigerate or freeze.
I am always surprised that boiled up fish heads smell so nice!