Thaw fish, if frozen. Brush fish fillets with lemon or lime juice. Rub desired seasoning evenly onto all sides of fish. Place the seasoned fish fillets in a well-greased wire grill basket. Grill in the wire basket on an uncovered grill directly over medium coals for 4 to 6 minutes for each 1 cm thickness f fish or just till fish begins to flake easily when tested with a fork. Meanwhile, for spread, in a small mixing bowl stir together mayonnaise or salad dressing, mustard, and honey to taste. To serve, spread the dressing mixture onto the cut side of focaccia slices or buns with watercress or lettuce, fish, additional dressing mixture, roasted red pepper or fresh tomato, and top slices or halves of bread. Makes 4 servings.