A fish stock forms the base of many soups and sauces in classical french cuisine. Known as a fumet in french, it consists of fish bones and scraps gently simmered with a bouquet garni and mirepoix. A mirepoix is the term for a mix of finely diced vegetables, whilst a bouquet garni is the term for a mix of herbs.
The mirepoix in this recipe consists of button mushrooms, fennel, leeks and onions, but other vegetables can be used to flavour the stock such as celery and carrots. To maximise flavour extraction, just make sure that the mirepoix is finely diced. The bouquet garni in this recipe consists of thyme, rosemary and parsley, without bayleaf. You can of course use whatever herbs you want. I have omitted bayleaf because the aromatic tea like aroma of bayleaf develops after a long simmer which a fish stock does not require.
A fish stock should only be cooked for 20 to 25 minutes. Any longer would cause the fish stock to lose its light delicate fresh flavour of the sea, and make it fishy and overly extracted. The fish bones and heads used in this recipe should be cleaned to stop the stock from becoming cloudy and bitter. This means removing as much impurities as possible from the bones. Gills should also be completely removed from fish heads. The easiest way to remove blood from the bones and heads is to soak the bones in water for 2 to 3 hours, whilst the easiest way to clean the bones and heads is with a toothbrush. If you don’t have time, a quick wash with cold water is better than nothing.
The kind of fish used for making the stock also matters. Other than flavour, the mouthfeel of the stock also matters. The higher the gelatin and collagen content of the fish bones and heads, the richer the mouthfeel of the stock. This means all flatfishes, such as turbot, halibut, sole and brill, make fantastic fish stocks. Oily fish on the other hand, can not be used to make fish stock as it gives the stock a heavy, fishy taste. This means oily fish such as tuna, mackerel and salmon cannot be used to make fish stock.
The Japanese version of fish stock is Dashi stock, you can find a recipe for that here.
In Japan, miso soup is sometimes made with a fish stock that sort of resembles fumet. A recipe for this can be found here.
Fish Stock Recipe:
- 1000ml of Water
- 750g of Fish bones
- 100g of Fennel
- 50g of Leeks
- 50g of Button mushrooms
- 30g Butter
- 25g of Onions
- 1 Bouquet garni (2 sprigs of thyme, rosemary and parsley)
- 20ml white wine
- Wash the fish bones and heads in water or soak them in cold water for 2 to 3 hours beforehand.
- Use a brush or sponge to remove any blood or dirt from the bones and heads.
- Cut up the fish bones and heads into smaller pieces using a scissors or knife.
- Peel and dice all the vegetables into small pieces. The smaller the pieces the faster the extraction.
- Melt the butter in a pan and sweat the vegetables, fish bones and heads without browning.
- Add in the bouquet garni and deglaze the pan with the white wine.
- Pour in the water and bring to barely a simmer.
- Simmer from 20 to 25 minutes on very low heat. Skim off any scum or dirt that rises to the top.
- Strain the stock once cooked and refrigerate or freeze.
- Fish stock should be used as soon as possible.
- Never boil you stock or it will go cloudy.
- The recipe doesn’t include salt because you usually season the final dish or sauce that the stock is used in. If you season the stock now perfectly, it would become overly salty if you were to reduce it down to a sauce.
- You can skim off the fish fat that rises to the surface with the scum if you want, or you can leave it in.
- Fish stock is one of those stocks that are much better fresh than frozen. If need be, it can be frozen almost indefinitely. Chicken and veal stock freezes much better than fish stock.