There are two basic ways to cure fish for smoking. One method is using a liquid brine cure. The second is a dry cure. I favor the dry cure for several reasons. First is ease of use, if you have a batch of cure in the freezer it takes only minutes to get a fillet prepped, wrapped and curing in the fridge. Dry cured fillets take up less room in the fridge. The texture and color of dry cured fish is more to my liking. And lastly, you can add seasonings to the base cure to give each fillet a different flavor profile.
This is the recipe for the dry cure I use. This makes enough cure for about 10 pounds of fish:
1 cup Mortons kosher salt (if you use Diamond Crystal, you will have to use more as it has larger grains)
2 cloves of garlic, finely chopped
2 cups firmly packed brown sugar
2 teaspoon ground ginger (I prefer to grind this myself in my mortar and pestle from cracked ginger)
1-2 teaspoons ground white pepper
½ teaspoon pulverized bay leaf
On a cutting board, sprinkle a little of the salt onto the chopped garlic, and mash to a paste with the point of a knife. In a small bowl, combine the garlic mixture with the remaining salt, the sugar, ginger, pepper and bay leaf. Mix this very well. Extra can be stored in the freezer.
90% of the fillets I smoke have the skin on. The instructions are written with this in mind. There are some specific notes for using skinless fillets.
You must use an adequate amount of cure for the job. An average side of salmon or steelhead is 10 to 14 inches long, but the thickness and width will vary. Oftentimes I will cut the tail section off and smoke it separately. I also cut off the belly strip. When I mention a cure depth of 1/8" to 1/4" in the glass dish or the plastic wrap, this usually requires about 2/3 to 3/4 of a cup for a side of salmon. If you trim the fillet down it will take less. Naturally if you are doing a 6" or 8" center cut from a fillet, you will use way less than 2/3 of a cup of cure.
The cure time is based on the thickness of the fillet, not the weight. You notice I list a range of time, this is to accommodate different thickness as well as personal preference for flavor. Some folks like a stronger and slightly saltier flavor. Time in the cure is 8 to 16 hours for a thick salmon fillet. A steelhead fillet will be thinner, so 6 to 8 hours works fine. Trout vary in size so the range of time is from 3 to 6 hours. With respect to cure time, disregard the length of the fillet, base it on thickness. Keep a log of your cure times and thickness so you can repeat a procedure you like. NOTE: For skinless fillets, sprinkle a layer of the dry cure on the top side as well. Skinless fillets will cure in about half the time because the cure is working from both sides.
Method 1 - Sprinkle a layer of cure about 1/8” to 1/4" deep into the bottom of a glass baking dish (don’t use metal) make sure it is a little wider and longer than the fillet. Place the fillet, skin side up, on top of the dry cure. Cover the dish with plastic wrap. Place in the refrigerator to cure.
Method 2 (preferred) - Take a piece of plastic wrap at least 6 or 7 inches longer than your fillet and lay it out on your counter. In the center of the plastic, sprinkle a layer of cure about 1/8" to 1/4" deep onto the plastic wrap, making sure the layer of cure is a little longer and wider than your fillet. (You will be using the extra plastic on the ends when wrapping the fillet). Place one fillet on top of the cure (skin side up), then fold the sides up and then the ends, leaving the seam on top. The wrapped fillets can be stacked. (I put them on a shallow tray just in case one leaks). Put the fillets into the fridge to cure.
This first picture shows the fillet on a layer of cure ready to be wrapped up.
Here are several wrapped fillets.
How The Cure Works - The moisture and oils in the fish will liquefy the dry cure and make a syrup which will cure the fish. After curing, rinse the fish very well under cold running water, rubbing gently to remove the syrup. I spend about 1 minute on each fillet rinsing and lightly scrubbing with my fingers. Blot dry with paper towels and put on a racks, then season with black pepper, garlic pepper, garlic powder, Montreal Steak seasoning, or whatever you like. Stay away from a rub with a lot of salt in it. Then air dry until tacky, at least 1 to 2 hours OR put back into the refrigerator for 4 to 6 hours. Resting overnight is my preferred method. Following the resting time, you can give the fillets a "shine coat" of oil by lightly brushing or spraying olive oil on them. A light coat is all that is needed, and the shine is especially nice on thinner trout fillets that may not have the higher oil content that salmon does.
Here is a fillet after curing - Note the syrup in the wrap
A photo of the syrup remaining in the plastic wrap
Here are some fillets following rinsing. These should be seasoned and returned to the fridge for resting. I prefer an overnight rest.
This fillet is ready for the smoker. Even raw it is darker than normal as this is wild caught Alaskan salmon. The amount of seasoning is typical, this one has garlic pepper and cracked black pepper.
This photo below (taken after smoking) shows a fillet with a heavier dose of cracked pepper. The "shine coat" of oil I mention below allows the pepper to soften slightly during smoking, and the amount is quite good especially if smaller portions are served.
Smoking Instructions - Prior to smoking, brush or spray a light coat of oil or Pam on the skin side of the fish and on your smoker rack. Place fish in the smoker with the skin side on the rack and hot smoke at 150° – 190° (grate temp).
Option 1 Traditional Flavor Wood Method: Start with equal parts of alder wood and apple wood. Instead of fist sized chunks of wood, I use smaller splits about a finger or two square. These are arranged in a wagon wheel pattern with the ends near the hotspot. I'll also mix a handful of chips into the lump. Apple and alder are mild woods and will keep the smokiness on the light side.
Check in about 30 minutes to make sure the skin is not sticking to the racks. (spray skin side with more oil if it starts to stick) Later in the cook, switch to cherry wood or maple wood and smoke until done. This will give the salmon a nice red color. There is no need for turning during smoking. If you have skinless fillets, trim a piece or foil or parchment paper 1/2" larger than the fillet. Oil the foil and lay the side of the fillet which would have had the skin onto the foil. (it will be the smoother side) Then set the fillet on the smoker rack. There will be no need to turn the fish during smoking.
Option 2 - Smoking With Hickory: Hickory is one of the stronger woods and is not typically used for something delicate like fish. However, if you use caution and small amounts of chips at a time hickory will produce a wonderful flavored fish. Using my Big Chief or Little Chief, I generally add about 2 tablespoons of fine chips, and add a few larger chips to the pan every 30 to 45 minutes. I do NOT empty the ashes when adding new chips. A mix of hickory and cherry is milder and as mentioned above, the cherry will help develop a red color. One of the few commercially smoked salmon that I really like is from The Honey Smoked Fish Company in Colorado, and part of their secret process is using hickory for smoke.
This is a over-under set up in my large Big Green Egg
Here is a fillet in my Big Chief box smoker
Here is an alternate set up using a pan with a rack on top
When Is It Done? - When the fish reaches about 120° internal, the fish will firm up and you might some white stuff start to ooze from the flesh. Relax, that's the serum albumen, a protein that is part of the blood. It will set up and congeal just like the albumen in egg whites. This is a signal that you need to watch the fish for doneness. (You can blot this off later with a paper towel after the fish has rested a few minutes). To avoid the albumen rising to the surface, keep your smoker temp 170° or below for the first 3 or 4 hours of the cook, ramping up the temp to 190° to 200° to get the fish to a finish temp.
Contrary to popular belief, you want to remove the fish before it actually flakes. 145° is considered a safe internal temperature, and I take mine off between 135° and 150° internal, depending on the moistness I want. If you want a drier product, just smoke to a higher internal temperature. Depending on your smoker, smoke times for thick fillets (3 to 4 lbs) can be 3 or 5 hours, thinner salmon or steelhead fillets may be in the 2 to 3 hour range, trout fillets will be less. Just keep an eye on the firmness and internal temperature. Sometimes, because of the weather I can't get my box smoker to a high enough temp to finish my fish to 145° - or 150°, so at the end of 4 hours I will move the fillets into a 175° to 190° oven to bump the internal temperature to where I want it. This might only take 10 minutes or so, keep an eye on it!!
In this photo the fish is around 120° internal, you can see the albumen starting to show.
This photo of the same fish is about 30 minutes later. The internal is now 130° and the albumen is very visible. Remember, it can be blotted off with a paper towel when the fillets come off the smoker. Had I been running the smoker at lower temps, the albumen would not have risen to the surface.
This fillet was smoked at a lower temperature in my Big Chief. Note that no albumen rose to the surface. I prefer my fillets to look like these.
TIP: For smaller fillets a water pan under the fish will prevent it from cooking too fast. Ice in the water pan works great also. The ice pan also will help if you have trouble maintaining low smoker temperatures regardless of the size of the fillets.
Serving - Serve hot, room temperature or chilled. I prefer to let the fish rest on the counter for an hour or so, then chill in the fridge overnight. This allows the moisture to stabilize, and allows for very nice slicing. A fine serrated knife works well for slicing. This will keep in the fridge for 3 to 4 days, but it very seldom lasts that long.