Cook the macaroni according to package instructions until al dente. Drain and rinse under cold water to cool. Set aside.

In a large bowl, whisk together mayonnaise, sour cream, Dijon mustard, apple cider vinegar, sugar, salt, and black pepper to make the dressing.

Add the cooled macaroni to the bowl with the dressing and gently toss to coat evenly.

Stir in the diced celery, red bell pepper, red onion, and chopped parsley until well combined.

Fold in the chopped hard-boiled eggs gently to avoid breaking them up too much.

Cover the bowl and refrigerate for at least 1 hour before serving to allow the flavors to meld together.

Before serving, give the salad a quick stir and adjust seasoning if needed. Garnish with extra parsley if desired.