Cold smoking is very hard to do at home because you need to have a smoker capable of keeping the temperature to 80 F or less. One way to do this is to have your heat source (smoke generator) far enough away that the smoke cools before it reaches your smoker.
Begin with either fresh or frozen salmon. Frozen is actually easier because some of the moisture is lost during freezing and thawing and that is what you are going to accomplish during the smoking process anyway.
If the fish is not already filleted, do it now and cut into even sized pieces. I like 2×4 inches. For larger species like King salmon or whole fillets, puncture the skin in several places to allow the salt to penetrate. You can also buy a hypodermic needle for horses at a feed store and inject brine into the thicker pieces. How to fillet salmon.
Now, you must make a brine of salt and brown sugar and, if you like a specific spice, go ahead and add it to the brine. I like to mix the brine 2:1 salt to brown sugar, but if you like a sweeter finished product, adjust it to your taste by adding more brown sugar. You must mix enough brine to immerse your fish in the solution completely. One way to tell if you have enough salt is to float an egg. For 5 gallons of water you will need 14 cups of salt and 7 cups of brown sugar. If it floats, you have enough salt. It is about 80%. I like to use a salometer!
A white five-gallon bucket works well for brining fish. Place your fish into the brine and place the bucket into refrigeration. Leave it there for 12 hours for thinner fillets and 24 hours for thicker fillets. Before removing from the brine, slice one of the pieces of fish to see if the brine has completely saturated the flesh. If not, leave it in the brine longer. Previously frozen fish takes less time than freshly caught product.
Remove fish from the brine and rinse under the cold running water for 1 hour for thinner fillets and 2 hours for thicker fillets. If you do not mind eating raw fish, try a slice to see how salty it is.
Remove from the rinse, rack, and place it under refrigeration to cure for at least 12 more hours. This allows the salt to even out. If you like dill on top now is the time to add it. I have tried rum with good results at this point.
Place in a smoker and set the temperature to 70 F. Smoke until the fish has a glazed look to it. It should take about 12-16 hours if you have good air circulation.
Take the fish out of the smoker and cool it down before vacuum sealing.
After packaging. If the fish was not previously frozen, be sure to freeze it for a couple of days for parasite control.
That is about all there is to smoking fish. It is a lot of trial and error and record keeping. Being in the smoking business, I have tried everyone’s smoking recipes and not two have been alike. So be inventive and try to make your own favorite smoked salmon recipe.