Start by bringing the water, citrus zest, brown sugar, and salt to a boil. Once the sugar and salt are dissolved, remove them from the heat and add the ice cubes to chill the brine. Set it aside.
Next, trim the side of the salmon, removing the belly fat and the tail end of the fish. You may also see a few bones on the backbone part of the salmon which should also be removed.
Add the salmon to a non-reactive dish and cover it completely by pouring it on the brine. If the salmon doesn’t want to stay under the brine, you can flip it over so that it is scaled side up.
Cover and keep it in the refrigerator for 12 to 24 hours. Any longer than 24 hours and it can become too salty. Remove the salmon from the brine and rinse it under cold water.
Place the salmon on a rack and pat it dry and let it cool for 2 hours to create the pellicle. Brush the smoker grates with a neutral-flavored oil where you plan to place the salmon.