Place fish on rack of a broiler pan coated with cooking spray; brush with lemon juice. Broil 5 to 6 minutes or until fish flakes easily when tested with a fork.
Combine mayonnaise and remaining 4 ingredients, stirring well. Spread mayonnaise mixture evenly over fish. Broil 1 minute or until lightly browned.
Tip: If flounder isn't available, you can substitute sole or orange roughy.