Because planks smoke and steam as they heat up, they improve grilled dishes by giving them a smoky flavour while still retaining moisture. Even better, planking shortens cleanup time dramatically by eliminating messy grates and stuck-on food. Fish is often served on a plank, but chicken with the skin on does well, too.
This is one of those rare dishes that tastes just as good cold as it does hot. If you decide to serve it cold, cook the fish for 3 minutes less because it continues cooking as it cools.