Make the marinade by mixing together the hoisin sauce, orange juice, honey, sriracha sauce, sesame oil and garlic powder together in a small bowl. Measure out ½ cup of the marinade and set aside. Place the salmon in a flat dish and pour the remaining marinade over the salmon. Flip the salmon a couple times to ensure that all the salmon is coated in the marinade. Cover with plastic wrap and place in the fridge for 3-4 hours. Flip the salmon every hour.
Smoke the fish for around 3 hours or until the internal temperature of the fish reaches 145°F (60°C).
During the smoking time, pour the ½ of reserved marinade in a small saucepan. Let it come to a low boil and let it reduce until it thickens and turns into a nice glaze. This takes about 10 minutes or so. Remove from heat.
Once the salmon has finished smoking, place it on a serving platter. Brush with the glaze. Sprinkle with toasted sesame seeds. Serve.