Soak cedar plank in water for at least an hour.

Whisk together the miso, mirin, vinegar, soy sauce, green onions, ginger, and sesame oil in a small bowl. 

Cover salmon in marinade for 30 minutes in the refrigerator.

Remove the fish from the marinade and season with salt and pepper.

Grill the salmon on the plank over direct heat for 15 minutes.