• Step 1: Cook the macaroni according to package instructions until al dente. Drain and rinse under cold water to cool completely.
• Step 2: In a large bowl, whisk together the mayonnaise, sour cream, vinegar, Dijon mustard, salt, and black pepper until well combined.
• Step 3: Add the cooked and cooled macaroni, diced celery, red onion, and bell pepper to the dressing. Toss gently to coat everything evenly.
• Step 4: If desired, fold in the chopped hard-boiled eggs and fresh parsley.
• Step 5: Cover and refrigerate the macaroni salad for at least 2 hours, or up to 3 days, to allow the flavors to meld.
• Step 6: Serve chilled, garnished with additional parsley if desired.