Boil the Pasta: Bring a large pot of salted water to a boil. Add the elbow macaroni and cook until al dente (usually 1–2 minutes less than the package directions). It is vital not to overcook the pasta, as it will continue to soften slightly once the dressing is added.

Rinse and Cool: Drain the pasta in a colander and immediately rinse with cold water. This stops the cooking process and removes excess starch, which prevents the macaroni from sticking together in a clump.

Whisk the Dressing: In a small mixing bowl, combine the mayonnaise, sour cream, apple cider vinegar, sugar, and mustard. Whisk until the texture is completely smooth and the sugar has dissolved. Season generously with salt and black pepper.

Prep the Mix-ins: While the pasta drains, dice your celery, red bell pepper, and green onions. Chop the hard-boiled eggs into bite-sized pieces.

The Big Mix: In a large chilled bowl, toss the cooled macaroni with the chopped vegetables and eggs. Pour the dressing over the top and use a rubber spatula to fold gently. Ensure every piece of pasta is well-coated without smashing the eggs.

The Chill Factor: Cover the bowl tightly with plastic wrap and refrigerate for at least 1 hour. This resting period allows the pasta to absorb the flavors of the dressing and ensures the salad is served at the perfect refreshing temperature.

Final Touch: Just before serving, give the salad a quick stir. If it looks a little dry, fold in a tablespoon of milk or extra mayo to loosen it up. Garnish with fresh parsley.