You might be wondering, why add any dressing to the salad the night before at all? Why not just wait until right before serving the salad to add all the dressing at once? While this is definitely something you can do and might save you a little extra time, it will also create a less flavorful pasta salad. This is because letting the noodles and vegetables in a macaroni salad rest for a minimum of one hour (and up to overnight) in at least some dressing is an important step in developing the flavor of the whole salad.
In fact, while the salad rests in the fridge, the flavors actually combine and then become more intense to create that signature, creamy sweetness. If you wait until the last minute to add the dressing, your pasta salad probably won’t be as good as it could’ve been. However, if you combine the chopped vegetables with the dressing and let it sit overnight before adding the macaroni in at the end, you might get slightly better results. The best choice overall for the most flavorful and creamy salad is still adding half the dressing first and then the second half before serving.
