Bring a large pot of salted water to a boil. Add the elbow macaroni and cook until al dente, about 8–10 minutes. Drain and rinse under cold water; set aside.

In a large mixing bowl, whisk together mayonnaise, white vinegar, mustard, sugar, salt, and pepper until smooth and creamy.

Add the cooled macaroni, chopped celery, carrot, and onion to the bowl. Stir gently to coat every piece of pasta with the tangy dressing.

Cover the salad and refrigerate for at least 4 hours, or preferably overnight, to let the flavors meld into the perfect pasta salad.

Before serving, give the dish a quick toss and adjust seasoning with extra salt or pepper if desired.