Preheat an outdoor grill for high heat and lightly oil grate.
Sprinkle chicken breasts with fajita seasoning, and grill for about 4 minutes on each side, or until no longer pink and juices run clear. Allow to cool, then slice into bite-size strips.
In a blender or food processor, combine mayonnaise, grated Parmesan cheese, sour cream, anchovies, green onions, parsley, Dijon mustard, chipotle pepper, garlic, and Worcestershire sauce. Blend until smooth.
Place romaine lettuce in a large bowl, and top with croutons, shredded Parmesan, and red, yellow, and orange pepper rings. Arrange chicken on top, then pour on the dressing.
