Soak the planks in water for at least 1 hour. You will need to weight the planks to be sure they stay submerged.
For the marinade
Stir together the rice vinegar, sesame oil, soy sauce, ground ginger, and garlic powder. Add the oil and stir well, using a fork.
Place the salmon fillets in a ziplock bag and add the marinade.
Marinate for at least 15 minutes, if you can...try for 45 minutes.
Grill the salmon
Preheat an outdoor grill for medium heat or about 350 degrees.
Place the planks on the grate and close the grill.
Wait for the boards to smoke and crackle just a little and then Place the salmon fillets onto the planks, skin side down, save the marinade.
If desired, add a slice or two of fresh lemon to the salmon.
Cover, and grill for about 15 minutes. Maintain a medium heat or 350 degree temperature, opening the grill as little as possible.
After 15 minutes, brush with saved marinade and grill for another 5 minutes or until done.
Fish is done when you can flake it with a fork. Don't overcook it. It will continue to cook while it rests.
Remove it from the grill and let it rest.
Notes
NOTE:
No cedar planks? I have made this many times without cedar planks and grilling right on the grill and it is very tasty. Simply add the salmon to indirect heat, skin side down, and follow the same steps.
No grill? You can use cedar planks in your oven! Preheat your oven up to 400 degrees and reduce the time from 15 minutes to 10 minutes before you add the brush of the marinade. Watch it closely, after that. It'll be about 15 minutes and it will be done.
Want to try this on the stove? Yep, this is tasty made up on the fry pan (skip the plank). You won't get as tender of a texture as the grill or oven method but you'll still be making this again and again. Pull out a heavy pan, cast-iron if you have it, and heat to medium heat, add the salmon skin side down (do not add oil to the pan!) and cover with aluminum foil. After 10 minutes brush it with marinade and fry it for an additional 5 minutes. Check for doneness.