Heat oil in large skillet. Add chicken; cook, stirring occasionally, until chicken is no longer pink. Remove from skillet; cool.
Combine dressing, mayonnaise and seasoning mix in large bowl. Add chicken, celery, bell pepper and green onion; mix until well coated.
Cover; refrigerate for 1 to 2 hours or overnight. Stir in cheese before serving. Serve on torn lettuce or lettuce leaves (optional).
Serving Size: 6