1. Heat a large nonstick skillet over medium-high heat; coat with cooking spray. Sprinkle fish evenly with Cajun seasoning and salt. Add 2 fillets to pan; cook 4 minutes on each side or until desired degree of doneness. Remove fish from pan, and keep warm. Wipe pan clean with paper towels; recoat with cooking spray. Repeat procedure with remaining 2 fillets.
2. While fish cooks, combine mayonnaise and next 5 ingredients in a small bowl. Serve with fish.