Bring a large pot of salted water to a boil. Add cavatappi pasta and cook for about 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, and sugar until smooth. Season with kosher salt and black pepper.

Return the chilled pasta to the bowl. Add a splash of vinegar or lemon juice and toss.

Pour about two-thirds of the dressing over the pasta and mix gently until coated. Let rest for 10-15 minutes.

Fold in diced red bell pepper, diced celery, diced red onion, and grated carrot.

Taste the salad and add remaining dressing as needed. Adjust seasoning with more salt or pepper.

Cover and refrigerate for 2-4 hours, or overnight. Serve chilled.

Stir before serving and garnish with paprika or fresh herbs if desired.