Of course, using smaller quantities, you can poach smaller whole fish, steaks or fillets by exactly the same method.
You can hire the fish kettle/poacher, either from a specialist caterer’s supplier or from many supermarkets, or substitute a very large and deep roasting tin. However, if you buy a fish kettle or fish poacher it is surprisingly good value, and although you probably won’t use it that often for its intended purpose, it can be useful for many other jobs where you need a large pot that can be used on the hob or in the oven. They are shaped like a long oval, which means that you won’t need as much liquid, and most importantly have a removable rack on which the fish sits, which makes it much easier to lift and drain the salmon once cooked. If you are going to use a roasting tin, make sure you have a rack (lined with several layers of aluminium foil into which you pierce draining holes) that fits it or you will almost certainly damage the cooked fish in trying to lift it out.
Let’s assume that you are going to cook a salmon weighing in the region of ten pounds/three kilogrammes. Depending on the size and depth of your fish kettle/poacher you will probably need around 10 pints/5 litres of the court bouillon – so you will need a stock pot that can cope with that amount of liquid plus a few pounds/kilos of veg. You could, of course, cook the stock in the fish kettle itself (without the rack and the fish!) to get a more exact amount. If you end up with a little less finished stock than you need, it can always be topped up with some boiling water.
There is no agreed recipe for a court bouillon – as I said, it is simply an aromatic vegetable stock used for poaching the fish. However, I would suggest that items in the first sentence below are pretty essential – total quantity around three pounds/one and a half kilos.
Carrots, onions, celery, garlic, juice and zest (no bitter pith) of a lemon, a few bay leaves and a good sprig or two of thyme, about twenty unground black peppercorns, and two or three large pinches of salt. To these essentials, as available and to your taste, you could add some (bulb/Florence) fennel, leeks and/or spring onions, orange (treated as the lemon), celeriac plus other herbs – herb fennel or dill would be an obvious choice. Some like to further acidulate the court bouillon by adding wine – say up to half a bottle. The acidulation helps release the flavours of the vegetables, and the wine, of course, adds its own.
Roughly chop or process the vegetables – you can include the onion/garlic skins for extra flavour and colour. Put into your cooking pot, and add the water. Bring to the boil, then reduce to a simmer. Court bouillon roughly translates as quickly or lightly cooked, and that is indeed all we need. Twenty minutes to half an hour at a simmer will get all the flavour we need from the veg, so strain it off after that time and discard the vegetables.
Now for the salmon. Place on the rack of the fish kettle/poacher. Spread out the lower flaps, or “skirt” of the belly of the fish to help support it – these will be cut away later, so don’t worry if they look untidy now. Some like to bend the fish into a slight “S” shape to help the presentation – once the fish has cooked, the proteins will set and hold the shape.
Bring the strained court bouillon to the boil in the fish kettle/poacher, and carefully lower in the fish on its rack – or you can boil the stock in another pot, place the fish on its rack in the kettle/poacher then ladle over the stock. Make sure the fish is completely covered. Bring the court bouillon to the boil, then immediately reduce the lowest possible simmer. Put the lid on. The fish kettle/poacher will almost certainly sit over at least two of your cooker hobs, so use them both to distribute the heat.
The fish will be cooked in around twenty minutes to half an hour – yes, that quickly. Do not, do not, do not overcook it. If you have a probe thermometer, the thickest part of the fish should read around 60 C/140 – it will continue to cook by residual heat once you have taken it out to drain. If you don’t have a thermometer, raise the fish on its rack and give the thickest part a squeeze – it should feel quite firm. Or, using a small, very sharp knife as a probe, check to see that the thickest parts are a pale pink rather than a reddy-pink and will easily come away from the bone – you know what cooked salmon should look like, don’t you? A final alternative check – if the dorsal fin feels loose and ready to “come away” from the fish, it should be cooked.
GET AN ASSISTANT FOR THIS PART OF THE JOB! Have ready a large plate, platter, or chopping board, large enough to hold the fish. Carefully raise the salmon on its rack from the liquid, keeping it horizontal, until you can slide the plate etc under it. Now move the fish/rack/platter to a convenient work surface and leave the whole thing exactly as it is for around ten to fifteen minutes.
(In the meantime, strain off the stock, allow to cool, and refrigerate/freeze for another occasion – you don’t want to waste it! You could reduce it down first, if you like.)
Preferably again with some help, and a combination of tools such as fish slice/egg flipper/palette knife, gently ease the fish from the rack onto whatever is to be your serving platter.
With a very sharp knife, cut away the “skirts” and discard: they will be overcooked, very fatty and full of bones. Now carefully cut through the skin along the back of the fish, behind the gills and just in front of the tail. Gently begin to peel off the skin – you may be lucky and it will come away in one piece per side, or you may have to do it in sections. If the fishmonger has not already removed the gills, cut them out now – this is not essential, but it improves the presentation. If the dorsal fin has come away, or was removed by the fishmonger, clean out the “groove” along the top of the fish, which may have some fat and bits of skin.
Once the skin is removed you will see that there is a light grey sheen over some of the flesh. You can very carefully scrape this away, but there is a danger that you will flake up the fish and it could end up looking worse – personally, I leave it as it is. In the “old days” chefs would use a combination of aspic and finely sliced cucumber emulating scales to cover this – I would suggest that you “leave it real”.
It is a good idea at this stage to lightly coat the flesh with a little olive oil, using a pastry brush or similar – this gives a nice sheen, and helps prevent the flesh from drying out. If you have followed my suggestion to cook the fish the day before your event, get the fish, on its platter, into the refrigerator as soon as it is cool enough – lightly cover with clingfilm/kitchen wrap.
Garnishing the platter: this is up to you, but I suggest that you keep it simple. You could make a bed of cold rice (perhaps cooked with a little turmeric so the final colour would suggest sand – a cheffy touch), but a simple lining of the bare parts of the platter with a nice arrangement of shredded lettuce, sliced cucumber and lemon and some sprigs of parsley will be enough. People have been known to put a cooked prawn or a wedge of lemon in the salmon’s mouth.
Whatever you do for presentation and garnish, remember the dish is Whole Poached Salmon, not Mad Garnishes with Whole Poached Salmon Hidden underneath!