Fill a large pot with water and bring it to a rolling boil. Add the macaroni and cook until tender. Follow package directions for the best pasta texture.

Pour the cooked macaroni into a colander. Drain completely and rinse under cold water. This stops the cooking process and helps maintain a firm texture.

In a large mixing bowl, combine mayonnaise, sour cream, mustard, vinegar, sugar, salt, and black pepper. Whisk until the mixture becomes smooth and creamy.

Finely chop the celery and red onion. Grate the carrot into small pieces. Smaller vegetables distribute evenly and improve the texture of the salad.

Add celery, carrot, onion, parsley, relish, and chopped eggs to the dressing. Stir gently until all ingredients are coated with the creamy mixture.

Place the cooled macaroni into the bowl. Stir carefully so every piece of pasta becomes coated with the flavorful dressing.

Taste the salad before chilling. Add extra salt or pepper if needed. Small adjustments can make a big difference in flavor.

Cover the bowl with plastic wrap or a lid. Refrigerate for at least one hour. Chilling allows the flavors to blend together perfectly.

Remove the salad from the refrigerator before serving. Stir gently to refresh the texture. Garnish with fresh parsley for extra color.