1. Cook the macaroni: Bring a large pot of salted water to a rolling boil. Add the elbow macaroni and cook according to package directions until al dente. This usually takes about 7-9 minutes. You want the pasta to be tender but still have a slight bite, not mushy.

2. Drain and cool the pasta: Once cooked, drain the macaroni thoroughly in a colander. Rinse it under cold water to stop the cooking process and cool it down completely. This is crucial for preventing the pasta from absorbing too much dressing and becoming mushy. Let it drain well.

3. Prepare the dressing ingredients: While the macaroni is cooling, finely dice your celery and red onion. Chop the fresh parsley and hard-boiled eggs. Having all your ingredients prepped makes the assembly process smooth and quick.

4. Whisk the creamy dressing: In a large mixing bowl, combine the mayonnaise, yellow mustard, apple cider vinegar, and granulated sugar. Whisk these ingredients together until the dressing is smooth and well combined. Taste and adjust the sugar or vinegar if you prefer it sweeter or tangier.

5. Combine all ingredients: Add the cooled and drained macaroni to the bowl with the dressing. Then, add the diced celery, red onion, chopped parsley, and chopped hard-boiled eggs.

6. Gently mix everything together: Using a large spoon or spatula, gently fold all the ingredients until the macaroni is evenly coated with the creamy dressing and all the vegetables and eggs are distributed throughout the salad. Be careful not to overmix, which can break down the pasta.

7. Season and chill: Season the macaroni salad generously with salt and black pepper to taste. Start with a little, mix, and then taste again, adding more as needed. Cover the bowl tightly with plastic wrap and refrigerate for at least 30 minutes, or ideally 2-4 hours, before serving. This chilling time allows the flavors to deepen and meld.