1. Cook macaroni according to package directions; drain.
2. Rinse with cold water and drain.
3. Combine macaroni, navy beans, carrots, celery, and parsley; mix well.
4. Combine next 5 ingredients; mix well.
5. Pour mayonnaise mixture over macaroni mixture, stirring well.
6. Chill at least 1 hour.
7. Line a salad bowl with romaine.
8. Spoon macaroni salad into bowl; arrange tomato slices around edge of salad.