To make the brine: In a saucepan, combine the brown sugar, salt, and apple juice and bring to a boil. Add the remaining brine ingredients, remove from the heat, and cool. This brine can be made 2 to 3 days in advance and kept in the refrigerator.
Submerge the salmon fillets in the liquid brine for at least 6 hours or overnight, refrigerated. Remove the salmon from the brine and place, uncovered, on a wire rack set in a sheet pan. Refrigerate the fillets for at least 6 hours, or overnight, to dry them out. (A dry fillet will take on smoke quicker than a moist fillet)
To smoke the salmon: In an outdoor grill, make a small fire using mesquite charcoal or briquettes. Once the fire has burned down to a hot bed of coals, after about 1 hour, place the soaked wood on the coals. Position the grate 8 to 12 inches above the smoking wood and place the salmon fillets on the grate.
Cover the grill and shut any open-air vents. After 5 minutes, check the heat of the grill; large fillets will be cooked and smoked through in approximately 30 minutes if the heat is low, about 300 to 350 degrees F, while a hotter fire will cook the fillets in 15 to 20 minutes. Serve the salmon hot off the grill.
Recipe courtesy of Wildwood Restaurant, Portland, OR