1. Soak Cedar Planks:

• Begin by preparing your cedar planks. Place the untreated cedar planks in a large container, sink, or baking dish. Cover them completely with warm water.
• Let the planks soak for at least 1 hour. Soaking longer (2-4 hours or even overnight) is even better, as it helps prevent them from catching fire on the grill and promotes more smoldering smoke. Weigh them down with something heavy if they float.

2. Prepare the Marinade:

• While the planks soak, prepare the marinade. In a shallow dish large enough to hold the salmon fillets in a single layer (or a large resealable plastic bag), whisk together the soy sauce, vegetable oil, rice vinegar, sesame oil, chopped green onions, grated fresh ginger, and minced garlic until well combined.

3. Marinate the Salmon:

• Pat the salmon fillets dry (if they had skin and it was just removed, or if rinsing). Place the salmon fillets into the soy mixture in the shallow dish, turning them to ensure all sides are coated.
• Cover the dish with plastic wrap (or seal the bag) and place in the refrigerator. Let the salmon marinate for at least 15 minutes, or up to 1 hour. Don’t marinate delicate fish like salmon for too long in acidic marinades, as it can affect the texture.

4. Preheat Grill and Heat Planks:

• Preheat your outdoor grill for medium heat (around 350-400°F or 175-200°C).
• Remove the soaked cedar planks from the water, letting excess water drip off.
• Place the wet planks directly on the preheated grill grates. Close the grill cover.
• Heat the planks for about 5-10 minutes, or until they start to dry out, lightly char, and begin to smoke and crackle just a little. This means they are ready for the salmon.

5. Grill the Salmon on Planks:

• Carefully remove the salmon fillets from the marinade, letting any excess marinade drip off. Discard the used marinade.
• Place the marinated salmon fillets directly onto the hot, smoking cedar planks on the grill.
• Close the grill cover.
• Grill the salmon for approximately 20 minutes. Cooking time will vary depending on the thickness of your salmon fillets and your desired level of doneness. The salmon is cooked when it flakes easily with a fork and reaches an internal temperature of around 135-145°F (57-63°C) for medium to medium-well. It will continue to cook slightly after being removed from the grill.

6. Rest and Serve:

• Carefully remove the planks with the salmon from the grill using sturdy tongs or a large spatula. You can serve the salmon directly on the planks for a rustic presentation (place planks on a heatproof surface), or carefully transfer the fillets to a serving platter.
• Let the salmon rest for a few minutes before serving.
• Garnish with extra chopped green onions or fresh parsley, if desired. Serve immediately.