12.5 Cooking fish and shellfish: moist heat

Moist heat suits fish and shellfish very well. Steaming keeps their natural flavor best and needs no fat. Poaching is popular for fish, which can then be served hot or cold. And what is called boiling, mostly for crustaceans, is really simmering.

For how each method works, see chapter 9: Moist heat: poach, simmer, steam.

Cooked fish must reach 70°C (158°F) inside.

Steaming

Steamed fish sits above a little boiling liquid in a covered pan, and the trapped steam cooks it gently. That keeps its flavor and most of its nutrients. The liquid can be plain water, or a court bouillon whose herbs, spices, aromatics or wine flavor the fish as it cooks.

Which fish. Mollusks such as clams and mussels, fatty fish such as salmon or sea bass, and lean fish such as sole all steam well. Cut portions to an even thickness of no more than 1 inch (2.5 cm), so they cook evenly.

Shellfish in their own pot. Mussels and clams need no rack. Put them in a pan with a splash of wine and cover it; the shells hold them up out of the liquid. They seldom need salt, because the liquor they release as they open is salty enough. Classic New England steamed clams come with some of their steaming broth, and steamed mussels with a sauce made from the wine they cooked in.

En papillote. Fish and shellfish can be sealed in parchment with herbs, vegetables, butter or sauce and baked in a hot oven. see chapter 9: En papillote Serve it at once, so the scented steam escapes when the paper is cut open at the table.

Steamed fish should taste clean and delicate and stay moist. Season it lightly. If the liquid will be served as a broth or turned into a sauce, season that liquid well. A low-fat sauce or a squeeze of lemon with steamed vegetables keeps the dish light; where fat is not a worry, beurre blanc or hollandaise works.

Poaching

Fish is often poached; shellfish rarely are. Squid is the exception: poach it quickly, then chill it for salads.

Which fish. Lean white fish, such as sole, bass and turbot, poach very well. So do some fatty fish, such as trout and salmon.

Two ways to poach.

• Submersion. The fish is fully covered by liquid, usually court bouillon, fish stock or fish fumet, and cooked until just done. Whole fish (wrapped in cheesecloth to hold its shape), tranches and steaks can all be poached this way. The sauce is more often made separately than from the liquid.
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• Shallow poaching. This mixes poaching with steaming. A fillet, tranche or steak sits on a bed of aromatic vegetables, in liquid that comes about halfway up its sides. This liquid is called the cuisson. Bring it to a simmer, cover the pan with buttered parchment or a lid, and finish on the stove or in the oven. The sauce is made from the reduced cuisson. If the fish is lightly sautéed before the liquid goes in, the method is really braising. see chapter 10: What braising is
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Temperature. Poach fish at 175°F to 185°F (79°C to 85°C). Start a whole fish in cold liquid and heat it slowly, which keeps it looking good. Start portions in liquid that is already simmering, which keeps their flavor and makes the cooking time easier to judge. Lower the fish in on a rack, and keep it fully under.

Seasoning. Poached fish gets all of its flavor from the liquid and the sauce, so the liquid must be good: a well-made court bouillon, fumet or stock, with shallot, onion or carrot and plenty of herbs and spices. If wine goes in, use a good one, since a poor wine can spoil a delicate fish. Lemon juice or zest suits the liquid, the sauce or the finished plate.

Serving. Fish poached by submersion goes with rich sauces, hollandaise or beurre blanc, or with a vegetable coulis for less fat. Cold poached fish takes a mayonnaise sauce such as sauce verte or remoulade. To serve it cold, cover it so it does not dry out, let it cool, and refrigerate it. Hot or cold, rice, pasta and steamed or boiled vegetables suit it.

Cooked food must drop from 60°C to 20°C within two hours, then from 20°C to 4°C within the next four hours.

Poached fillets with lemon-parsley butter show shallow poaching at small scale:

• Soften onion and celery in oil.
• Lay the fillets on top, and add water, lemon juice, salt, bay leaf and parsley.
• Cover the pan and simmer for about 8 minutes, without turning the fish, until it is opaque and flakes.
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• Move the fish with a wide spatula and serve it with lemon-parsley butter.

Simmering shellfish

"Boiled" lobster, crab and shrimp are not really boiled. They are simmered, whole and in the shell. They are sturdier than fish, but they still toughen and overcook if the liquid boils hard. Their hard shells shield the delicate meat as they cook.

Seasoning. Do not season the shellfish itself before cooking. Flavor the liquid instead: salted water or court bouillon, sometimes with a bottled seafood seasoning or a sachet of pickling spice.

Method. Adding food cools the water, and a large volume of water comes back to the boil faster, so use as much as you can.

• Bring the liquid to a boil.
• Add the shellfish, let the liquid come back to the boil, then lower it to a simmer.
• Cook until done.
• Serve at once, or plunge the shellfish into ice water if they will be eaten cold.
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Timing. For simmered shellfish, the clock is the best test. Times depend on size and on how fast the water returns to a simmer.

Simmering times for shellfish. The lobster-tail times are for a tail simmered in salted water, 1 teaspoon of salt to each quart.

Serve hot simmered shellfish with lemon wedges and melted butter, and cold ones with a tomato cocktail sauce. Corn on the cob and boiled potatoes are the usual sides.

Shellfish cooked in a sauce or soup need the same care. For an oyster stew, warm the oysters in butter over low heat only until their edges curl. For creole shrimp, add the peeled shrimp to the finished sauce for just 5 more minutes. For a clam chowder, boil fresh clams only until the shells pop open.

How to tell good from overcooked

Cooked fish should separate easily into flakes. Past that point it shrinks and turns tough and dry. Overcooked shellfish turns tough too.