From America's Test Kitchen Season 10: Salmon—Indoors and Out
Roasting a salmon fillet can create a brown exterior, but often at the risk of a dry, overcooked interior. The best roasted salmon should have moist, flavorful flesh inside, with a contrasting crisp texture on the outside.
In order to ensure that the salmon fillets would cook evenly, we cut a whole center-cut fillet into four pieces. We roasted the fish at a low temperature and achieved the buttery flesh we were after, but no browning—and the fillets were a little mushy from the rendered fat. Taking the opposite approach, we put the fish on a preheated baking sheet and started the oven at a high temperature to firm up and brown the exterior. This gave us a crust, but we still needed to get rid of the fat; cutting slits in the skin released the fat rendered by the high heat. Lowering the temperature as soon as we put the fish in the oven enabled it to cook through gradually after the initial blast of heat, so it didn’t dry out. Now we had the contrast between moist interior and crisp brown exterior that we wanted. Salmon is rich and flavorful all on its own, but we devised a couple of easy no-cook relishes that can be served alongside for even more flavor.
To ensure uniform pieces of fish that cook at the same rate, buy a whole center-cut fillet and cut it into 4 pieces. If your knife is not sharp enough to easily cut through the skin, try a serrated knife. It is important to keep the skin on during cooking; remove it afterward if you choose not to serve it. To serve, top with any of the related relishes.