From America's Test Kitchen Season 1: How to Cook Salmon
Cooking delicate salmon can be tricky. Even using a nonstick skillet, it’s still easy to break the occasional fillet. Introduce that same fillet to a grill, and you’ve got a real challenge. We wanted grilled salmon with a tender interior and crisp skin, and with each fillet perfectly intact.
Part of the solution lay in a procedure we developed to clean the grill thoroughly: Place an overturned disposable aluminum pan over the grate as the grill warms up, trapping hot air and superheating the grate. Just like in a self-cleaning oven, the high heat causes grease and debris to disintegrate. By replacing the disposable pan with foil pressed against the grate, we bumped the temperature up higher, making the technique even more effective. We chose thicker salmon fillets, which could stand the heat of the grill for a little while longer before the first turn. To prevent the fish from sticking, we dried the fish’s exterior by wrapping it in kitchen towels and “seasoned” our cooking grate by brushing it over and over with multiple layers of oil until it developed a dark, shiny coating. After laying the fillets on the grate, we easily flipped each fillet without even the tiniest bit of sticking.
If your fillets are less than one and one-half inches thick, decrease the grilling time by roughly thirty seconds per side. If using a gas grill, heat it for ten minutes and then grill the salmon over direct heat for four to five minutes per side. To test fillets for doneness, either peek into the salmon with the tip of a small knife as described below or remove the salmon from the grill and squeeze both sides of the fillet gently with your fingertips (raw salmon is squishy; medium-rare salmon is firm, but not hard).