Step 1

In a pot over medium heat, bring about 4 quarts of water to a boil. Add elbow macaroni and cook according to the package's direction.

Step 2

Drain well and transfer to a large bowl.

Step 3

While still hot, drizzle the apple cider vinegar and add the carrots and onions. Gently toss to evenly distribute and let stand for about 10 to 15 minutes.

Step 4

In another bowl, combine mayonnaise, milk, brown sugar, salt, and pepper. Whisk together until smooth.

Step 5

Add half of the mayonnaise dressing over the macaroni mixture, and gently toss together all of the ingredients to coat. Let stand for about 15 to 20 minutes.

Step 6

Add the remaining half of the mayonnaise dressing to the pasta mixture and toss again to distribute. Garnish with chopped green onions, if desired.

Step 7

Cover the bowl with a tight-fitting lid and refrigerate for about 2 to 3 hours to completely chill and the flavors to meld. Serve cold.