Bring a large pot of salted water to a boil. Add the elbow macaroni and cook until al dente, following the package instructions. Drain the pasta and rinse under cold running water to stop the cooking process. Allow to drain thoroughly and set aside.

In a large mixing bowl, whisk together mayonnaise, sour cream, mustard, apple cider vinegar, sugar, paprika, salt, and black pepper until smooth and creamy.

Add the cooked, cooled pasta to the dressing. Gently fold in the chopped eggs, celery, green onions, and pickle relish (if using). Mix gently to ensure even coating without mashing the eggs.

Cover the bowl with plastic wrap or transfer the salad to an airtight container. Refrigerate for at least 1 hour to allow the flavors to meld and develop.

Before serving, stir the salad to redistribute the dressing. Sprinkle additional paprika on top and garnish with freshly chopped parsley. Serve chilled as a side dish or main course.