Boil a pot of salted water and cook the elbow macaroni according to package instructions until al dente. Drain and set aside to cool.

In a large bowl, whisk together mayonnaise, mustard, and apple cider vinegar until smooth.

Add the cooled macaroni to the bowl with the dressing, and gently fold in the chopped celery, red bell pepper, onion, and hard-boiled eggs.

Season with salt and pepper to taste, stirring until everything is well-coated.

Cover the salad and refrigerate for at least one hour to let the flavors meld.