SAUCE: Measure all ingredients into a blender or food processor. Blend untl smooth. Season to taste, if necessary. Refrigerate for at least 2 hours for flavours to blend. Reserve 1 1/2 cups for the sauce and use remaining sauce to brush on salmon during cooking. Brush salmon steaks with butter. Preheat grill to medium.
Place salmon steaks on grill. Cook for 4-5 minutes per side, brushing cooked sides with sauce. Serve salmon steaks immediately with reserved sauce.