Place first 8 ingredients in a blender or food processor; process until almost smooth.
Sprinkle fish with 1 teaspoon pepper and salt. Place fish, skin sides up, on a grill rack coated with cooking spray; grill 5 minutes on each side or until fish flakes easily when tested with a fork. Remove skin from fillets; discard skin. Break fish into chunks.
Place greens and basil in large bowl; add 1/4 cup cucumber dressing, tossing well. Arrange salad on 4 plates. Divide salmon chunks evenly among salads; top each serving with 2 tablespoons cucumber dressing and 2 tablespoons mango.