Rinse the onions and chop finely and add to the bowl.
Crush the garlic clove and grate the ginger and add to the bowl, stir well and then leave it for 20-30 minutes to get the flavors to blend.
Smoke
Get your grill started using indirect heat (using the lid). Apply 1 chunk of oak wood and run it at 120° C / 250° F.
While the grill is coming up to temp: use a small oven pan or similar that fits the grill. Cover it with aluminum foil for easy cleaning later. Place the salmon in the pan and cover it with the dressing.
Place the pan with salmon on the grill, add a wood chunk to the glowing embers and close the lid. Make sure the salmon is on the indirect side only, not over the glowing embers. Let it smoke until the inner temperature of the salmon reaches 52° C / 125° F.