Soak the cedar plank in water for at least 2 hours before grilling—this prevents it from burning and creates the flavorful smoke that defines this dish. While the plank soaks, prepare your mise en place: zest the lemon and slice it into 1/4-inch rounds, finely snip the fresh chives, and measure out all your seasonings and butter. This advance prep ensures smooth execution once the grill heats up.
In a small bowl, combine the softened butter with the lemon zest, chives, garlic powder, and honey, stirring until well mixed. Set aside at room temperature. Pat the salmon fillet dry with paper towels, then season both sides generously with kosher salt and freshly cracked black pepper. I find seasoning the fish just before grilling prevents the salt from drawing out too much moisture.
Remove the soaked cedar plank from water and place it directly on the grill grates. Preheat the grill to 400°F with the plank inside for about 10 minutes—this allows the plank to dry slightly and begin releasing that distinctive smoky aroma. You'll know it's ready when you see wisps of smoke rising from the plank.
Carefully place the seasoned salmon fillet skin-side down on the hot cedar plank. Close the grill lid and cook undisturbed for 15 to 25 minutes, depending on the thickness of your fillet and your grill's heat distribution—the salmon is done when it flakes easily with a fork and reaches an internal temperature of 125-130°F for medium-rare. The cedar plank insulates the fish and infuses it with subtle wood smoke while keeping it incredibly moist.
When the salmon is cooked through, open the grill and generously spread or dollop the compound butter from Step 2 over the hot fish, allowing it to melt into the flesh. Let it rest on the plank for 1-2 minutes to absorb the buttery flavors. Transfer the salmon directly to a serving platter and garnish with the lemon slices from Step 1. I like to spoon any melted butter from the plank over the top before plating—it's liquid gold.