To prepare the marinade: In a small bowl whisk together the syrup and soy sauce. Pour the marinade into a large plastic resealable bag, and add the fillets. Press out the air and seal the bag tightly, then turn the bag several times to distribute the marinade Set in a large bowl and refrigerate for as long as possible (a minimum of 4 hours, but ideally 24 hours to do it justice). Turn salmon every few hours.
Place pepper on a small plate. Remove salmon from marinade and generously spray both sides of each fillet with oil. Pat top side only into cracked pepper to coat. Grill fillets, pepper side up, over Direct High heat for about 6 minutes, turning once halfway through grilling time. Avoid overcooking the fillets. Salmon is best when the colour has turned to a pale pink, but the fish is still moist throughout. Serve immediately on warmed plates.
