1. Soak Cedar Planks Thoroughly:

• Begin by preparing your cedar planks well in advance. Place the untreated cedar planks in a large container, your clean sink, or a large baking dish. Cover them completely with warm water.
• Let the planks soak for a minimum of 1 hour. For best results and more smoke (and less chance of fire), soak them for 2-4 hours, or even overnight if you have the time. Ensure they are fully submerged; you might need to place something heavy on top to keep them down if they float.

2. Prepare the Ginger-Soy Marinade:

• While the planks are soaking, prepare the delicious marinade. In a shallow dish that’s large enough to hold the salmon fillets in a single layer (or use a large resealable plastic bag), combine the ⅓ cup soy sauce, ⅓ cup vegetable oil, 1 ½ tablespoons rice vinegar, 1 teaspoon sesame oil, ¼ cup chopped green onions, 1 tablespoon grated fresh ginger, and 1 teaspoon minced garlic.
• Whisk these ingredients together until the marinade is well combined.

3. Marinate the Salmon:

• Pat the salmon fillets dry with paper towels. Place the salmon fillets into the dish with the soy mixture. Turn the fillets to ensure all sides are coated with the marinade.
• Cover the dish with plastic wrap (or seal the bag, pressing out excess air). Place it in the refrigerator and let the salmon marinate for at least 15 minutes, or for up to 1 hour for deeper flavor. Avoid marinating delicate fish like salmon for excessively long periods in acidic marinades, as it can start to affect the texture.

4. Preheat Grill and Heat Cedar Planks:

• About 15-20 minutes before you plan to cook, preheat your outdoor grill to medium heat (approximately 350-400°F or 175-200°C).
• Remove the soaked cedar planks from the water, letting any excess water drip off.
• Place the wet cedar planks directly on the preheated grill grates. Close the grill cover.
• Heat the planks for about 5-10 minutes. You want them to start to dry out, possibly char slightly on the bottom, and begin to release a smoky aroma and maybe even crackle a little. This indicates they are hot and ready for the salmon.

5. Grill the Salmon on the Planks:

• Carefully remove the marinated salmon fillets from the marinade, allowing any excess marinade to drip back into the dish. Discard the used marinade (it has touched raw fish).
• Open the grill and carefully place the marinated salmon fillets directly onto the hot, smoking cedar planks.
• Close the grill cover.
• Grill the salmon for approximately 20 minutes. The exact 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 when gently prodded, and its internal temperature reaches around 135-145°F (57-63°C) for medium to medium-well. Remember that salmon will continue to cook for a few minutes from residual heat after you remove it from the grill.

6. Rest and Serve:

• Once cooked to your liking, carefully remove the cedar 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 wonderfully rustic presentation (be sure to place the hot planks on a heatproof surface!), or you can carefully transfer the salmon fillets to a serving platter.
• Let the salmon rest for about 5 minutes before serving.
• Garnish with extra chopped green onions or fresh parsley, and perhaps some lemon wedges on the side, if desired. Serve immediately and enjoy the smoky, savory flavor!