In a small bowl, combine the first five ingredients; mix well. Remove 1/2 cup to a saucepan; simmer until heated through. Set aside remaining mixture for basting.
Sprinkle salmon with lemon-pepper. Place on grill with skin side down. Grill, covered, over medium heat for 5 minutes. Brush with the reserved brown sugar mixture. Grill 10-15 minutes longer, basting occasionally, until fish flakes easily with a fork. Serve with the warmed sauce.