When I lived in Kent, Washington I used this grill smoked salmon technique quite often. I didn't have a smoker, but I did have a gas grill out back on the covered deck. After some trial and error, I was able to make good smoked salmon without using a real meat smoker.
Gas grill smoking isn't that difficult. I just had to make adjustments that would enable me to smoke in my grill.
Those were the main grill-smoking issues I had to resolve. Once I had those figured out, it was easy to whip up a batch of grill smoked salmon.
Maintaining Grill-Smoker Temperature
Maintaining the correct temperature required a few special
"adjustments". My grill at that time had three burners, one on each end
and one in the middle. I used just one of end burners for heat. When the
wind blew, I'd use the burner on the side the wind was blowing against.
That way, the smoke would travel over the salmon more efficiently.
I'd start with the burner set as low as it would go. A foil packet of smoking wood was placed over the burner. Then a pan (I used a 9"x13" cake pan) of water was placed on the grate, directly over the packet of smoke wood. The water helped regulate the temperature by absorbing some of the heat. The pan would be filled with cold water, except on hot days, when I'd use ice water. The burner was adjusted to keep the temperature between 160-170°F.
If ice water didn't keep the grill-smoker cool enough, I'd crack the lid open enough to bring the temp down. As the water heated up, I'd either replace it with cold, or I'd open the lid a little more. If the wood was still smoking, I'd replace the water and keep the lid shut, which would keep the smoked concentrated around the salmon. If there was no smoke happening, I'd just open the lid a little more.
Producing Wood Smoke While Grill Smoking Salmon
I finally settled on foil packets directly over the burner as my
preferred method of smoking. I tried placing water-soaked chunks
directly over the burner, but those would dry and catch fire. Then the
grill temperature would skyrocket, ruining the smoking salmon.
I've used a bread pan, putting the wood chips, chunks or pellets in the bottom, and wrapping the top tightly with foil. That worked well, but I couldn't put the grate over it for the water pan. I still use the bread pan method when smoking meats at a 225-250°F. It works great for that!
I'd use two additions of smoke wood for a batch of salmon - one at the beginning, and when it petered out, a second addition went in. I used about 1/4 cup of chips, or a 2 inch cube of wood for each addition...both water soaked for a half-hour. Pellets do not get soaked in water. And they put out more smoke than wood does. Depending on the type you use, try 1 to 2 tablespoons per addition. Remember to position your grill so the wind, if any, pushes the smoke over the cooking salmon.
Knowing The Grill - Hot Spots, Cool Areas
Typically, the area close to the lit burner will be hotter. When I used the elevated rack that sat at the rear of my grill, it was considerably hotter there than at grate level. Each grill has its own ways, and that's something you'll need to figure out as you go.
After the salmon is brined and dried off, oil the skin side and place it
(the skin side) on the oiled grate of your preheated and smoking
grill-smoker. Do what's necessary to maintain 160-170°F. When you learn
where the hotspots are, rotate the pieces of fish from hot to cool, and
cool to hot. Do this about every 45 minutes, or whenever you check the
Measure the temperature of the salmon with an instant read analog or digital thermometer. If you have one, use a remote cooking thermometer. You'll be able to monitor the internal temp of the salmon without opening the grill.
Smoked salmon is done at 140-145°F. At that temperature the salmon is barely done. If you prefer your fish well done, let the temperature rise to 155°F. It may be a little drier, but that may be more to your liking. Which is OK! Either way, let the salmon rest, covered with foil on the counter, for 20 minutes before serving. The juices will have a chance to gel, which keeps them in the fish, where they belong!
Grill smoked salmon can be made successfully when you apply a few simple "adjustments" to the cooking process. You CAN live without a smoker...but I wouldn't recommend it!