Soak the cedar plank for at lest 2-3 hrs, overnight preferably.
Mix all the Shellac ingredients in a small pot, bring to a boil, and cook for 1 minute or so, stirring the whole time, it will thicken. Remove from heat. Let cool. This step can be done well in advance, even the day before.
Heat the grill to medium high heat.
Place the fish on the plank, pour the Maple Shellac over the fish, place the plank/fish on the grill.
Turn the heat to medium low and cook for 15-20 minutes.
Serve on the plank.