Cook and drain the pasta according to package directions, adding an extra 1-2 minutes of cooking time. Transfer the pasta to a large bowl and toss it with the apple cider vinegar while still warm.
Using a box grater or the grater attachment on food processor, grate the carrot and onion.
In a large mixing bowl, whisk together the mayonnaise, vinegar, milk, sugar, salt, pepper and grated onion.
Fold in the cooked macaroni and grated carrots. Serve cold or at room temperature.
Keyword easy, pasta, side dish, summer, vegetarian