Soak an untreated cedar plank in water for at least one hour (longer if you have the time). You will want to weight it down with something heavy (brick or large rock) so that it stays submerged. I buy my cedar planks at the hardware store – 6 foot lengths of 1” x 6” untreated fence pickets – and cut them into 18” lengths.
When ready to grill, either build a charcoal fire in half the grill or turn grill burners on high for 10 minutes. Meanwhile, score the salmon (not through the skin) every 3 inches or so. Mix the oil, garlic, and dill and rub over the salmon and into scored areas to coat.
Place soaked cedar plank on the hot grill grate, close lid, and watch until the grill starts to smoke—maybe 5 minutes. Put the salmon onto the hot plank and move off direct charcoal heat or turn the burners to low. Cook until salmon is opaque throughout, usually 20-30 minutes. The USDA recommends that fish be cooked to an internal temperature of 145 degrees for safety. Let rest 5 minutes and serve. Make the best use of that hot grill and pair this with a grilled vegetable medley.