Individual portions of salmon make for quick and easy meals, but they're not very impressive as the centerpiece of a special-occasion meal. For those days, a full-sized fillet of salmon makes a much more imposing entree. Fillets of market-sized salmon typically range from 2.5 to 3.5 pounds in weight -- enough of a variation to be alarming for inexperienced cooks. With a roast of beef or pork, it would genuinely affect your cooking time. That's not the case with salmon and other fish, though. Because of its flat shape, the cooking time is determined primarily by thickness.
The 10-Minute Rule
While the oven is heating, take a moment to measure the fillet at its thickest point. As long as you bake the fillet at a temperature of 400 to 450 F, it should take approximately 10 minutes per inch of thickness. That means a cooking time of 10 minutes for an inch-thick fillet, or 15 minutes for one that's 1 1/2 inches thick.
Surprisingly, the rule even holds true if you're broiling the salmon. The only difference is that he fillet's surface browns and develops a crust, because of the broiler's intensity.
Preparing the Fillet
You can cook the fillet with or without its skin, but leaving the skin intact helps the fillet hold together. Ask your fishmonger to scale the salmon before filleting it. Keep the salmon on ice or in a cooler all the way home, and refrigerate it immediately.
Heat the oven to 425 F. Place the fillet on a clean cutting board, and trim away any rough edges or pieces of fin .
Feel for any bones or bone fragments near the thick end of the fillet, where the ribs sometimes elude the boning process.
Check for pinbones, a line of short, stiff bones running between the salmon's center line and its thick edge. If you find any, pull them out with fish tweezers or a pair of scrupulously cleaned needlenose pliers.
Transfer the fillet to a parchment-lined baking sheet.
Fold the thin belly meat underneath the fillet, so it's doubled over, then fold the thin end of the tail underneath as well. This step is optional, but it gives the fillet a more uniform thickness and helps it cook evenly.
Baking the Fillet
Season the fillet any way you wish, from a simple grinding of salt and pepper to your favorite sauce or herbs. Some cooks prefer to brush the surface of the salmon with oil or a glaze to keep it from drying, but that's seldom an issue if you observe the 10-minute rule. Slide the sheet pan into the oven and make a note of the time.
After the appropriate number of minutes has passed, check the salmon at its thickest point. It should flake readily but still be slightly translucent in the middle. An instant-read thermometer inserted horizontally into the thickest portion of the fillet should register an internal temperature of 140 F. The salmon's internal temperature will continue to rise for a few minutes after it comes out of the oven, finishing at the recommended temperature of 145 F.
A Few Variations
Sometimes, your favorite salmon recipe can have an impact on its cooking time. If you like to cook salmon en papillote -- inside a foil or parchment pouch -- allow an extra five minutes' cooking time. A thick layer of sauce or glaze can have a similar effect, because its moisture must cook away before heat can penetrate to the fish below.
If you immerse your fillet entirely in a sauce, that requires further adjustments. If the sauce itself is already hot, another five minutes' cooking time will usually be enough. If you cover the salmon in a cold or room-temperature sauce, it might require as many as 20 extra minutes. Watch to see when the sauce starts to bubble and steam. At that point, it should take roughly another 10 minutes for the salmon to be fully cooked.