Add macaroni noodles to a pot of boiling water and cook for a few minutes longer than the package directions suggest. (You want your noodles to be a bit overcooked for it to be authentic.) Drain and transfer to a large serving bowl.

While the macaroni noodles are still hot, add the vinegar, carrot, and onion. Stir until combined, then allow it to cool and absorb the vinegar for about 10 minutes.

Meanwhile, in a small bowl, whisk together the mayo, milk, and sugar.

Add the mayo mixture to the macaroni noodles and mix until well combined.

Add more mayo, if needed, and salt and pepper to taste.

Cover and refrigerate until you're ready to eat, then gently stir the salad once more before serving.