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, Dijon mustard, apple cider vinegar, sugar, salt, and black pepper until smooth.
Pour the dressing over the cooled macaroni and mix well to combine.
Add the diced celery, bell pepper, red onion, sweet pickle relish, chopped parsley, and chopped hard-boiled eggs to the macaroni. Stir gently until all ingredients are evenly coated with the dressing.
Cover the bowl with plastic wrap and refrigerate for at least 1 hour to allow the flavors to meld.
Before serving, give the salad a good stir and adjust seasoning if necessary.
Notes
For a crunchier texture, add 1/2 cup of diced pickles or chopped nuts.
To make it lighter, substitute Greek yogurt for half of the mayonnaise.