To prepare cedar planks: Soak planks in water 1 hour. Heat oven to 375 F.
Wash, oil and bake planks about 10 minutes to cure.
Heat grill to medium-high heat for indirect grilling.
In small bowl, mix honey, miso, rice vinegar, soy sauce and garlic. Cut salmon to fit planks. Season salmon with salt and pepper, to taste; spread miso mixture on flesh side. Let stand at room temperature 10-15 minutes.
Lay salmon on planks skin side down. Place planks on grill adjacent to heat source and close lid. Cook 15-25 minutes, depending on thickness, until internal temperature reaches 125-135 F. Transfer salmon and planks to platter and serve.