Bring a large pot of salted water to a boil. Add the cavatappi pasta and cook for 8-10 minutes until al dente. Drain and rinse under cold water.

In a mixing bowl, whisk together mayonnaise, sour cream, white vinegar, Dijon mustard, sugar, salt and pepper until smooth.

Toss the cooled pasta with the dressing, adding lemon juice for brightness, and mix gently.

Let the pasta salad rest for 10-15 minutes at room temperature to meld flavors.

Fold in red bell pepper, celery, red onion, and carrot, mixing gently.

Adjust the creaminess by adding remaining dressing as needed, and check seasoning.

Cover and refrigerate the salad for 2-4 hours, or ideally overnight before serving.