I use this recipe every single time I cook fish:

Topping
•3 tbsp margerine, melted but not hot
•1 lemon, juiced
•1 tsp ground black pepper
•1-2 tsp minced garlic
•1/4 onion finely chopped
•1 medium sized tomato, seeds removed and chopped finely.

Fish
•whole 2-5 lbs salmon or Hatchery Steelhead fillet.

Mix all the 'topping' ingredients well in a small bowl. Texture should be somewhat like salsa or chutney. Place fillet of salmon on a hot bbq grill, skin side down, directly on grill. Cover fillet with topping, doing your best to keep the topping from falling off the salmon (some will undoubtedly fall off, just do what you can!). Cover salmon and topping with a single sheet of aluminum foil, and form the foil to fit gently around the fish.

Cook ~10 minutes (or more, if fillet is thick!) to desired doneness. Recommend a medium-high or even high fire under the fish. The fish will usually separate quite easily from the skin, simply remove the fish by portioning with a knife or spatula, using your spatula to remove portions from the skin which should stick to the grill...and serve! Note you will not be turning the fish, this is a one-side and done cooking technique. Flip saptula over and scrape skin off grill while hot to ease with cleanup.