Prepare elbow macaroni as indicated on the box, drain, and set aside to cool.
Combine mayonnaise, sugar, dijon mustard, apple cider vinegar, milk, salt, and black pepper in a medium bowl and stir to combine.
Place pasta, red onion, red bell pepper, cucumber, carrots, and tuna (if you are using tuna) in a separate bowl. Pour sauce over top and stir to combine.
Refrigerate for 2 hours and Enjoy.