Cure the Fish. Mix together the brine ingredients and place your fish in a non-reactive container (plastic or glass), cover and put in the refrigerator. This curing process eliminates some of the moisture from the inside of the fish while at the same time infusing it with salt, which will help preserve the salmon.
You will need to cure your salmon at least 4 hours, even for thin fillets from trout or pink salmon. In my experience, large trout or char, as well as pink, sockeye and silver salmon need 8 hours. A really thick piece of king salmon might need as much as 36 hours in the brine. Never go more than 48 hours, however, or your fish will be too salty. Double the brine if it's not enough to cover the fish.
Dry the Fish. Take your fish out of the brine and pat it dry. Set the fillets on your cooling rack, skin side down. Ideally you'd do this right under a ceiling fan set on high, or outside in a cool, breezy place. By "cool" I mean 60F or cooler. Let the fish dry for 2 to 4 hours (or up to overnight in the fridge). You want the surface of the fish to develop a shiny skin called a pellicle. This is one step many beginning smokers fail to do, but drying in a cool, breezy place is essential.
Smoke your fish. Start by slicking the skin of your fish with some oil, so it won't stick to the smoker rack. It is important to bring the temperature up gradually or you will get that white albumin "bleed" on the meat. Start the process between 140F and 150F for up to an hour, then finish at 175F for final hour or two. To keep temperatures mild, always put water in your drip pan to keep temps consistently low.
Baste the Fish. After an hour in the smoker, baste the fish with birch or maple syrup, or honey; do this every hour. This is a good way to brush away any albumin that might form. In most cases, you will get a little. You just don't want a ton of it. Even if you can't control your temperature this precisely, you get the general idea. You goal should be an internal temperature of about 130F to 140F. if you want a lighter smoke, finish the salmon without smoke or in a 200F oven
You must be careful about your heat. Other than failing to dry your salmon long enough, the single biggest problem in smoking salmon is too high heat. If you've ever seen salmon "bleed" a white, creamy substance, that's a protein called albumin. If you see lots of it, you've screwed up; a little is normal. If you cook a piece of salmon at too high a heat, the muscle fibers in the meat contract so violently that they extrude albumin, which immediately congeals on the surface.
Cool and Store the Fish. Once your fish is smoked, let it rest for 10 minutes before serving. If you intend to store it for longer, set it on the cooling rack for an hour before you put it in the fridge. Once refrigerated and wrapped in plastic, smoked fish will keep for 10 days. If you vacuum-seal it, the fish will keep for up to 3 weeks. Or freeze your fish for up to a year.
