Begin by bringing a large pot of salted water to a rolling boil. Add in the elbow pasta and cook it for about 8–10 minutes, or until it's al dente. Stir occasionally to prevent sticking. Once done, drain the pasta in a colander and set it aside to cool.

In a spacious mixing bowl, whisk together the mayonnaise, sour cream, red wine vinegar, sugar, and yellow mustard. Add a pinch of salt and black pepper to taste.

Once the elbow pasta has cooled, drizzle it into the bowl with the dressing. Gently fold the pasta into the dressing until every piece is thoroughly coated.

Finely dice the celery, red pepper, and red onion. Stir these ingredients into the pasta mixture, ensuring even distribution.

Cover the bowl with plastic wrap or transfer the salad to an airtight container. Refrigerate for at least 2 hours, or ideally overnight.