To sear: Heat the oven to 400 degrees. In a cast-iron skillet, melt about 2 tablespoons unsalted butter. Add one 6 to 8-ounce, skin-on salmon fillet, with the skin side down. Cook for 3 minutes over high heat to brown the skin, spooning some of the melted butter over the top of the fish as it cooks.
Transfer the pan to oven. Roast until fish is just cooked through, 8 to 10 minutes.
Note: for even crispier skin, lightly dust the skin side of individual portions of fillet with flour before placing them in the pan.
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To broil: Broiling gives a tasty and attractive burnish to the top (skinless) surface of fillets or steaks, and it is not necessary to turn the fish.
A delicious way to do this is on a wooden plank. Fish markets and cookware stores sell untreated cedar and apple wood planks, but never use pine as it will give the fish the flavor of resin. The plank should be soaked in water before use. Otherwise, use a sheet pan with sides, lined with foil if you like.
Here’s a simple method:
Heat the oven broiler to very hot. Position the oven rack so the salmon is no farther than four inches from source of heat.
Broil salmon three to five minutes, watching carefully, until top is attractively browned and fish is slightly undercooked in the middle. If you like salmon done this way, remove from oven and transfer to serving platter. Otherwise, shut off broiler and leave salmon in hot oven another three to five minutes, to desired degree of doneness.
Note: A foolproof treatment for broiled salmon is to spread regular mayonnaise, either store-bought or homemade, on salmon fillets before cooking. This flavorful coating – it’s an old trick – will become beautifully dappled and toasty-looking, and keep the fish moist.