1. Soak cedar plank in water at least 30 minutes.
2. Remove pin bones from salmon, if necessary, and coat fish evenly with rub. Cover with plastic wrap or foil, and chill until ready to grill.
3. Drain plank, and grill over medium-high heat (350° to 400°) for 3 minutes or until grill marks appear. Remove from grill. Place salmon, skin side down, on heated side of plank. Top with lemon slices.
4. Place planked salmon on grill, cover, and grill 20 minutes or until desired degree of doneness. (Check occasionally to make sure edges of plank don't ignite.) Garnish, if desired.