After years in the Pacific Northwest I’ve learned to appreciate a nice salmon filet. Unfortunately, I’ve seen most cooks ruin this king of fish by either overdoing their recipe with complex sauces and hiding the taste of the fish itself or overcooking the filet so that it is dry and grainy or treating salmon, not surprisingly, like they would a piece of fish.
Salmon, unlike most other fish, is best prepared almost exactly the way you would prepare a prime steak. When it doubt, think, “Would I do this to a dry aged prime porterhouse?” and follow that experience.
These tips apply to any filet but I’ve generally found that line-caught Alaska King Salmon is the most flavorful. When available, the salmon from the Copper River are the best due to their extra fat developed from the particularly cold water. Coho salmon is also excellent but being smaller the fillets tend to be less flat in shape and are harder to cook evenly. Avoid Keta or Pink salmon, these are really not in the same league as their cousins and avoid farm raised Atlantic Salmon (called that no matter where it actually was farmed) because their restricted diet, lack of exercise and lack of exposure to cold water tend to make them flavorless and dry.
Try to get a filet that’s about the right size for your meal. I usually plan on about ½ lb. per person but a 1/3 lb. portion may work for some people. Realize that you will lose water and fat in cooking so much less than this is going to be a snack and not a meal for the same effort.
Since you’re cooking the filet as one piece, try to get a filet that is as even in thickness as possible. This avoids having the edges overcooked by the time the center is medium rare.
If the filet is frozen, allow time for thawing. If this isn’t possible, carefully thaw it in a microwave.
Before you do any preparation work, let the salmon get to room temperature. This is very important in getting a filet that is medium on the outside with a good crust and a medium rare center. A cold salmon will end up with either an overcooked, dry exterior or a raw interior.
If needed, slice the salmon filet vertically (from spine to belly) to get the right size piece.
If your filet has a flap of thin belly meat, slice it off and cook it separately. If you leave it on it will not cook evenly. But do not throw it out or give it to the dog unless you are feeling very generous since if you cook it first, this thin strip can be a great treat for the chef to nibble on while the rest of the fish cooks.
Dry the salmon on all sides with paper towels. This keeps your heat going into the filet rather than being wasted in boiling off the water.
Remove any pin bones with a pair of needle nose pliers. (A typical kitchen tool here in the Northwest). These are the secondary rib cage and even the best fish monger occasionally misses one. Using pliers and pulling straight out allows you to remove the bones without tearing chunks out of the meat.
Liberally coat all sides of the filet with a neutral tasting, high smoke point oil. This isn’t for flavor but is to conduct heat and to help form a crust.
Salt all sides of the salmon and rub the salt into the oil. This will draw proteins to the surface and will also help to form a good crust. Yes, you should use more salt than you think you really should.
You should use a frying pan or other grill surface that can hold heat and is large enough for the filet. Cast iron works well.
Lightly oil the surface and bring to a very high heat.
Once the oil has reached the “shimmer” stage you should place the filet in the pan skin side up. This order matters for two reasons, the heat in the pan is highest at this time since the fish hasn’t cooled the pan yet and getting a crust on this exposed surface is easier now than when it is flaky from being cooked. (This is why you should always brown a filet before vacuum sealing it if you cook it sous vide)
Avoid the temptation of moving the filet or jiggling the pan. You should let it cook on this side until the sides are opaque and lighter colored at least 2/3rds of the way up the side. You will probably see little cream colored liquid beads form. This is a great sign. It is beads of melted fat escaping and is a sign of a good, fatty fish which is the mark of a juicy and flavorful filet.
Once you have reached the 2/3rds level, you should flip the filet with a good spatula being careful not to tear the browned surface. If possible, place the filet in an unused section of the pan but if there is not enough room for that to be possible, try rotating it 90 degrees as well so as much of the filet is on fresh hot surface.
If you have a thermometer you can gauge doneness by temperature (you are shooting for a rare temperature so that carryover heat will bring it to a medium rare temperature by the time the filet has rested). If not, you can tell by touch once you have some experience but you may just have to separate two of the flakes in the filet and look at the color. You want the internal color to be pinkish red in the center but not transparent. If it is a dark pinkish opaque color you’re ready to pull the fish.
At this point, place the filet skin side down on a plate or cooling rack for 3-5 minutes. You can tent it with aluminum foil to trap the heat but do not wrap the filet in foil or the moisture escaping will ruin the crust you spent time forming.
After the rest, put on a plate and serve.