- Step 1: Cook the Macaroni: Bring a large pot of salted water to a boil. Add the macaroni and cook according to package directions until al dente. Overcooking will result in a mushy salad. Drain the macaroni well and rinse with cold water to stop the cooking process. This step is crucial for achieving the desired texture. 
- Step 2: Prepare the Dressing: In a large bowl, whisk together the mayonnaise, white vinegar, sugar, and milk until smooth. Adjust the sweetness and tanginess to your liking by adding more sugar or vinegar, a little at a time, tasting as you go. 
- Step 3: Combine Ingredients: Add the cooked macaroni to the bowl with the dressing. Gently fold until the macaroni is evenly coated. If using, stir in the finely chopped celery and onion. 
- Step 4: Season and Chill: Season with salt and pepper to taste. Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, to allow the flavors to meld and the salad to chill thoroughly. This resting period is essential for the salad to develop its signature taste and creamy texture. 
- Step 5: Adjust Consistency (If Needed): Before serving, check the consistency of the salad. If it seems too dry, add a little more milk, one tablespoon at a time, until it reaches the desired creaminess. Give it a final stir and serve cold.
For a tangier flavor, substitute apple cider vinegar for white vinegar. For a richer taste, use Japanese mayonnaise (Kewpie). Adding a small amount of grated carrot can provide a touch of sweetness and color.