Boil a large pot of salted water and cook the elbow macaroni until al dente.
Drain the macaroni and rinse under cold water to cool it down.
In a large mixing bowl, combine mayonnaise, Dijon mustard, and apple cider vinegar.
Add the cooled macaroni to the dressing and mix well.
Incorporate diced bell peppers, chopped red onion, diced celery, and sweet peas into the bowl.
Season with salt and pepper to taste.
Stir everything until evenly coated with the dressing.
Cover and refrigerate for at least 30 minutes.
Before serving, garnish with chopped parsley.