1. Preheat grill to medium-high heat.
2. Heat butter in a small saucepan over medium heat; cook 3 minutes or until browned. Add nuts; cook 1 minute, stirring occasionally. Add couscous; cook 1 minute, stirring occasionally. Add wine and broth; bring to a boil. Cover, remove from heat, and let stand 5 minutes. Fluff with a fork; stir in rind, juice, 1/4 teaspoon salt, and black pepper.
3. Combine white pepper and next 4 ingredients (through 1/4 teaspoon salt) in a small bowl. Coat salmon fillets with cooking spray. Sprinkle fillets with spice mixture. Place salmon on a grill rack coated with cooking spray. Grill over medium-high heat 4 minutes on each side or until desired degree of doneness. Serve with couscous.