Cook the elbow macaroni according to package instructions until al dente. Drain and rinse under cold water to cool. Set aside in a large mixing bowl.
In a separate bowl, whisk together the mayonnaise, apple cider vinegar, Dijon mustard, sugar, salt, and black pepper until smooth.
Pour the dressing over the cooled macaroni and mix until well combined.
Add the diced celery, red bell pepper, red onion, peas, and chopped hard-boiled eggs to the macaroni. Gently fold in the ingredients until evenly distributed.
If using, sprinkle the chopped parsley on top for garnish.
Cover the salad and refrigerate for at least 1 hour before serving to allow the flavors to meld.