For those of us who love fish, the skill of being able to judge accurately whether fish is fresh or not is vital. The most important thing to remember when buying or sourcing fish is that fresh fish never smells, it just has the merest scent of the sea, reminiscent of fresh seaweed.
Fresh fish looks lively and stiff, and the skin glistens. By the time the eyes are sunken, the fish is a week old. Stale fish looks distinctly miserable; the gills will be dark and the skin can be gritty and dry, and it has a strong fishy smell. It doesn’t matter if the fishmonger winks at you and says he caught it himself, if it smells, it’s not fresh.
That’s all straightforward enough, but between the time fish is really fresh and the time it is stale there are several days during which time it will be gradually deteriorating. It is during this period that it is most difficult to tell just what condition it is in, particularly if the fish has been filleted and cut into small pieces.
You have to judge by the color and smell. Check that the flesh of white fish is white and not at all discolored, and that the under-skin of flat fish is quite white and not yellowing.
For those who live far from the sea, frozen fillets can be excellent. Good firms freeze their fish in prime condition within hours of being caught, so it is far preferable to buying “fresh” fish that is several days old.
First decide whether you need to scale the fish. Grey sea mullet has scales as large as a thumbnail and definitely needs scaling. Other fish with smaller scales, such as plaice or sea bream, need not necessarily be scaled. Some fish either have tiny scales or are completely smooth, and don’t need to be scaled at all.
If you’re poaching the fish, there is no need to scale it as the skin will be taken off after cooking. I always leave the skin on in this case as I feel the scales help to keep more flavor in. If you’re pan-grilling, however, the fish must be scaled, because you’ll want to eat the delicious crispy skin — and crispy scales are quite a different matter!
Remove the scales by holding the fish by the tail and pushing against the scales with the back of a knife from the tail to the head on both sides.
Flat fish are gutted in the boats as soon as they are caught because their insides deteriorate very quickly, so you just need to wash them out thoroughly. You can use the method below to gut any round fish, such as salmon, mackerel, pollock, and grey sea mullet.
It’s best to gut fish close to the sink. Put a cutting board on the drainer and cover with a couple of sheets of newspaper. If you are cooking the fish whole, you don’t need to remove the head. However, if you plan to fillet the fish you may find it easier to remove the head before gutting, for ease of handling.
In larger fish like salmon, a teaspoon with a pointed end is a great help because you can just run it along the backbone. Rinse the fish well again and refrigerate until needed.
When gutting herring, you’ll want to save the roe, so slit the belly carefully so as not to damage the roes. Detach the roe from the intestines and discard the latter. Rinse the roe gently, refrigerate, and use as quickly as possible.
Use this method for flat fish such as plaice, sole, halibut, brill, or turbot. If you are going to fillet a fish with any kind of finesse, allow yourself the luxury of a sharp filleting knife with a flexible blade.
Use this method for round fish such as salmon, haddock, cod, pollock, grey sea mullet, or mackerel. Use a sharp filleting knife with a flexible blade.
When filleting salmon, remove the flesh all in one piece and remove the pin bones with salmon tweezers afterwards.
Put the fillet of fish skin side down on the board. Cut through the flesh, down onto the skin at the tail end. Hold onto the skin then pull the tail end and, with the knife at a 45-degree angle, half push, half saw the flesh off the skin. If the knife is at the right angle, there should be no waste. Use the skin in fish stock.
Sprinkling a fish with salt on both sides and leaving it for even 10 minutes before cooking dramatically improves both the flavor and texture. Even if the fish is not spanking fresh, it firms up the flesh and imbues it with extra flavor. This is often common practice in Japan. It’s particularly worthwhile with salmon.
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