Step 1: Cook the Macaroni: Bring a large pot of salted water to a boil. Add the elbow macaroni and cook according to package directions, until al dente. Overcooking will result in a mushy salad. Drain the macaroni thoroughly and rinse with cold water to stop the cooking process. Ensure all excess water is removed.
Step 2: Prepare the Dressing: In a large bowl, whisk together the mayonnaise, milk, white vinegar, sugar, salt, and pepper until smooth. Taste and adjust seasonings as needed. Some prefer a sweeter dressing, while others favor more tang; personalize to preference.
Step 3: Combine Ingredients: Add the cooked and cooled macaroni, grated carrot, diced celery, and chopped sweet onion (if using) to the bowl with the dressing. Gently fold all ingredients together until the macaroni is evenly coated. Take care not to overmix, which can lead to a pasty texture.
Step 4: Chill: Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or preferably overnight. This allows the flavors to meld and the salad to develop its signature creamy texture. Stir gently before serving.
Step 5: Serve: Serve cold as a side dish to grilled meats, Hawaiian BBQ, or as part of a plate lunch. Garnish with a sprinkle of paprika or chopped parsley for added visual appeal, if desired.
For a tangier flavor, increase the amount of vinegar. For a sweeter salad, add a touch more sugar or a tablespoon of condensed milk. If the salad seems too thick after chilling, add a splash more milk to reach the desired consistency.