1. Combine lemon juice and lime juice in smal glass baking dish. Rinse salmon fillets; pat dry with paper towels. Place salmon fillets in juice mixture; marinate about 10 minutes, turning once.
2. For dill sauce, place mayonnaise, mustard and chopped dill in small bowl. Stir until thoroughly combined; set aside.
3. Preheat broiler Lightly spray rack of broiler pan with nonstick cooking spray. Remove salmon fillets from juice mixture; pat dry with paper towels. Place salmon fillets on prepared rack.
4. Broil samon fillets 4 inches from heat until salmon flakes in center when tested with a fork, about 3 to 4 minutes on each side. Serve salmon fillets with dill sauce. Garnish with fresh dill and lemon wedges, if desired.