Boil the Pasta: In a large pot of salted boiling water, cook the macaroni according to the package instructions until perfectly tender.
Cool the Noodles: Drain the cooked macaroni and rinse it thoroughly under cold tap water to stop the cooking process and cool the noodles completely.
Mix the Dressing: In a bowl large enough to fit the entire salad, make the dressing. Whisk together the mayonnaise, apple cider vinegar, sugar, relish, mustard, salt, and pepper until perfectly smooth.
Combine: Add the diced celery, shredded carrots, diced bell pepper, diced red onion, and the cooled macaroni into the large bowl with the dressing.
Coat and Adjust: Stir everything together gently until the pasta and vegetables are well coated in the creamy dressing. Taste the salad and adjust the seasoning with extra salt and pepper as needed.
Chill and Serve: Cover the bowl tightly and chill in the refrigerator for at least 1 hour before serving to let the flavors develop. Enjoy!