Cook the macaroni: Bring a large pot of salted water to a boil. Add the macaroni and cook according to package instructions until al dente. Drain and rinse under cold water to cool.

Prepare the dressing: In a large bowl, whisk together mayonnaise, apple cider vinegar, Dijon mustard, sugar, salt, and black pepper until smooth.

Combine ingredients: Add the cooled macaroni, diced celery, red bell pepper, red onion, and chopped parsley to the bowl with the dressing. Stir well to coat everything evenly.

Add eggs: Gently fold in the chopped hard-boiled eggs to avoid breaking them up too much.

Chill: Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld.

Serve: Give the salad a quick stir before serving. Adjust seasoning with additional salt and pepper if needed.