Cook the elbow macaroni according to package instructions. Drain and rinse under cold water to cool.

In a large bowl, combine the cooled macaroni, celery, red bell pepper, red onion, and sweet pickle relish.

In a separate bowl, whisk together the mayonnaise, apple cider vinegar, Dijon mustard, salt, and black pepper.

Pour the dressing over the macaroni mixture and stir until well combined. If using, fold in the chopped hard-boiled eggs and green onions.

Cover and refrigerate for at least 30 minutes before serving to allow flavors to meld.