Soak cedar plank for at least 2 hours or up to overnight. Optional: add approx 2 cups of white wine or beer into soaking water to give cedar plank extra flavor.
Preheat grill to about 450 degrees F.
When cedar plank has finished soaking, pat dry. Place salmon filet on the cedar plank skin side down.
Season with salt and pepper, then sprinkle chopped dill over salmon.
Arrange the lemon slices on the salmon, then top with fresh thyme.
Grill for 15-20 mins. Salmon should flake easily with a fork when cooked.