Put eggs in a saucepan, cover with cold water by 1 inch and bring to a boil. Cover, remove from heat and let stand for 12 minutes, then cool in ice water, peel and chop.
Meanwhile, boil macaroni in water with the tablespoon salt until fully tender. Drain, toss with vinegar and spread in a shallow dish for 10 minutes to stop steaming.
Mix mayonnaise, sour cream, mustard, sugar, dressing salt and pepper. Fold through cooled macaroni with celery, bell pepper and onion.
Add chopped eggs gently, cover and refrigerate for at least 30 minutes; the listed prep time includes this chilling.
Stir lightly before serving cold and refrigerate leftovers within 2 hours.