Where is it written that when you poach a fish, it has to be salmon?
Of course, poached salmon has its charms, but there are other fish in the sea -- and in the river.
In fact, poaching may be the best way to appreciate the pure flavor of any of them, from delicate sole filets to whole striped bass.
The technique is simple: Lower a whole fish or filet into barely simmering liquid, cover it, cook it briefly and lift it out. The fish becomes lightly infused with the flavors of the poaching medium, yet it’s cooked so gently that the natural, nuanced flavor of the fish takes a front seat. When you poach a fish, flavors emerge that would be obscured by the high heat of other cooking methods, such as searing or broiling. The texture is beautiful too: soft, tender and moist.
When it comes to creativity, there’s no better canvas. Poached fish can be served hot, cold or anywhere in between. It can be adorned with just a slice of lemon and sprig of parsley, or dressed up with any one of a wide variety of sauces -- vinaigrette, beurre blanc or flavored mayonnaise. Or you can serve it a la nage, garnished with vegetables used to flavor a court bouillon along with a little of the bouillon as a sauce.
Poaching is as simple and forgiving a way to cook fish as you’ll ever find. The only slightly tricky parts are determining when the fish is done and getting it out of the poaching liquid and onto a platter in one piece. Yet one or two attempts will turn anyone into a pro. And a broken filet can always be prettied up with garnishes.
The easiest fish to poach have firm flesh that will hold up without breaking apart. Monkfish, albacore and other tuna, arctic char, turbot, skate and halibut all are good candidates. And whole fish are easier to lift out of the water than filets.
A whole striped bass is a natural for poaching. They commonly are found in the 1 1/2- to 2-pound size, which is convenient for this technique. Whole red snapper and catfish also work well. Small whole mackerel -- a dark, oily-fleshed member of the tuna family -- hold up nicely during poaching.
Next, think about the poaching liquid.
Fish can be poached in water flavored with herbs and vegetables or slices of citrus; a court bouillon made of water, wine, lemon juice or vinegar, aromatic vegetables and other flavorings; or a fumet of fish stock and seasonings.
Use more assertive herbs and seasonings for the stronger-flavored types of fish and a more delicate treatment for mild fish, so its flavors are enhanced, not masked. Let the poaching liquid simmer with any aromatics before adding the fish for a more flavorful liquid.
Our Mediterranean striped bass is poached in salted water flavored with carrot, onion, lemon, parsley and bay leaf.
For the Japanese-style mackerel, the medium is a dashi-based broth. Dashi is bonito-seaweed stock; we use dashi-no-moto, an instant form, as a handy shortcut. You can find it in Japanese markets or the Asian section of many supermarkets and using it is as easy as dropping a bouillon cube into hot water. With fresh ginger and green onion added, it makes an excellent poaching liquid.
For petrale sole -- a more delicate filet -- we used a poaching liquid of mild white wine, chicken broth and lemon court bouillon.
Whatever liquid you use, it’s important that it remains just below a simmer, with the water barely moving and no air bubbles breaking the surface -- this is sometimes called “shivering.” Heat that is too high will cause the fish to toughen, break apart and lose flavor. During poaching you’ll want to remove the cover and check to see that the liquid is shivering, not boiling. If you notice any bubbles, leave the lid slightly ajar and reduce the heat.
You don’t need fancy equipment, though a fish poacher is a great piece of equipment to have. It’s just an elongated pot with a rack on the bottom, and can be bought for as little as $20. Because the pan is tailored to fit fish, you’ll use less stock, and the rack makes lifting the cooked fish a less-risky proposition.
But really, you can do without a fish poacher, just improvise: A roasting pan or skillet does nicely, depending on the size of the fish. The pan needs to be just large and deep enough to hold the fish and enough poaching liquid to barely cover it.
And you can rig up your own lift-rack: Just place the uncooked fish on a length of foil long enough to cover the bottom of the pan and extend up beyond the sides. When the cooking is done, you can grasp the ends of the foil, and cradle the fish out and onto the plate. For smaller fish or filets, a large spatula works fine.
A good tip for fragile fish is to lay parchment paper on top to help prevent it from breaking up during poaching. Whole fish and filets also can be wrapped in cheesecloth to help keep their shape.
As far as cooking time, the rule of thumb for poaching is 10 minutes for each inch of thickness. If you’re poaching a whole fish, check for doneness by piercing the fish with the tip of a knife along the backbone near the thickest part. Filets should also be checked at the thickest part. When in doubt, check the temperature: At 160 degrees, it’s done. (If you’re serving it cold, you may want to remove it from the heat when it is slightly underdone and allow it to sit in the poaching liquid and cool to room temperature before chilling. The cooling time in the poaching liquid will add flavor.)
Finally, you’ll want to add some colorful touches to finish your dish. To give you an idea of the possibilities, we finished our three dishes with a wide range of flavors.
The striped bass rests on a bed of Swiss chard, with fried capers for a little crunch. The poached sole has a beautiful emerald basil-garlic oil and champagne vinaigrette drizzled over the top. And the mackerel is dressed up with a crumbling of loose green tea and cold soba noodles.
It’s enough to make us forget about salmon entirely.