From America's Test Kitchen Season 9: Fish Made Easy
When salmon is poached incorrectly, not only is it dry, but the flavor is so washed out that not even the richest sauce can redeem it. We wanted irresistibly supple salmon accented by the delicate flavor of the poaching liquid, accompanied by a simple pan sauce—all in under half an hour.
We started our tests with a classic court-bouillon, which is made by boiling water, wine, herbs, vegetables, and aromatics and then straining out the solids. But discarding all those vegetables seemed wasteful for a simple weeknight supper. Using less liquid—poaching the salmon in just enough liquid to come half an inch up the side of the fillets—allowed us to cut back on the quantity of vegetables and aromatics; in fact, a couple of shallots, a few herbs, and some wine were all we needed to solve the flavor issue. However, the part of the salmon that wasn’t submerged in liquid needed to be steamed for thorough cooking, and the low cooking temperature required to poach the salmon evenly didn’t create enough steam. The solution was to increase the ratio of wine to water. The additional alcohol lowered the liquid’s boiling point, producing more vapor even at the lower temperature. Meanwhile, the bottom of the fillets had the opposite problem, overcooking due to direct contact with the pan. Resting the salmon fillets on top of lemon slices provided sufficient insulation. For a finishing touch, after removing the salmon, we reduced the liquid and added a few tablespoons of olive oil to create an easy vinaigrette-style sauce.
To ensure even-sized pieces of fish, we prefer to buy a whole center-cut fillet and cut it into four pieces. If a skinless whole fillet is unavailable, follow the recipe as directed with a skin-on fillet, adding 3 to 4 minutes to the cooking time in step 2. Remove the skin after cooking (see instructions below). This recipe will yield salmon fillets cooked to medium. If you prefer rare salmon (translucent in the center), reduce the cooking time by 2 minutes, or until the salmon registers 110 degrees in the thickest part.