Soak cedar plank completely submerged in cold water for 2 or more hours. Combine marinade and then brush on both sides of fish. Allow fish to marinate refrigerated 30 minutes. Remove plank from water and pat dry the side the fish will be placed on.
To cook in the oven, first preheat to 425 degrees F. Place fish on plank and bake 15-20 minutes.
To cook on the barbecue, first preheat to its highest setting. Once heated, if you have a two-burner barbecue, turn one side off and lower the other to medium. Set fish on plank and place plank on the unlit side of the barbecue. If you have a one burner barbecue, set to its lowest setting before setting on the plank. Close the lid and cook about 15-20 minutes, or until fish is cooked through. Keep a spray bottle handy should the board ignite. Set plank on serving tray and garnish with lemon and dill.