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. Avoid overcooking.
Step 2: Drain and Cool: Drain the macaroni immediately and rinse under cold water to stop the cooking process. This step is crucial for preventing the macaroni from becoming mushy. Transfer the cooled macaroni to a large mixing bowl and allow it to cool completely.
Step 3: Prepare the Dressing: In a separate bowl, whisk together the mayonnaise, milk, sugar, rice vinegar, salt, and pepper until smooth and well combined. Ensure the sugar is fully dissolved.
Step 4: Combine and Mix: Pour the dressing over the cooled macaroni. Gently fold the ingredients together until the macaroni is evenly coated with the creamy dressing. Be careful not to overmix.
Step 5: Add Optional Vegetables: If desired, add the finely diced celery and onion to the salad. Gently stir to incorporate the vegetables evenly throughout the macaroni salad.
Step 6: Chill and Rest: Cover the bowl tightly with plastic wrap and refrigerate for at least 2 hours, or preferably overnight. This chilling period allows the flavors to meld together and the macaroni to fully absorb the dressing.
Step 7: Serve and Enjoy: Before serving, stir the macaroni salad gently to redistribute the dressing. Add more milk if the salad seems too dry. Serve chilled as a side dish at barbecues, potlucks, or any gathering.
Optional Tips: For a tangier flavor, add an extra teaspoon of rice vinegar. To reduce the richness, substitute half of the mayonnaise with plain yogurt or sour cream. For added texture, include a sprinkle of chopped green onions before serving.