01 -
Boil elbow macaroni in salted water until very soft and tender, then drain thoroughly and transfer to a large mixing bowl.
02 -
Add grated onion, grated carrot, half of the mayonnaise, milk, apple cider vinegar, sugar if using, salt, and pepper to the cooked macaroni. Stir well to combine.
03 -
Cover the bowl and refrigerate the mixture for at least 2 hours, preferably overnight, to allow flavors to meld and noodles to absorb the dressing.
04 -
Before serving, stir in the remaining mayonnaise until fully incorporated. Serve chilled, optionally garnished with chopped green onions.