Bring a large pot of salted water to a boil over high heat. Add the elbow macaroni and cook until al dente, approximately 8-10 minutes. Drain the pasta and rinse with cold water to stop the cooking process and cool it down.
While the pasta cooks, prepare the vegetables. Finely chop the celery and dice the red bell pepper. Set aside for mixing.
In a large mixing bowl, combine the mayonnaise, sour cream, yellow mustard, white vinegar, and a pinch of salt and pepper. Whisk until smooth and well blended. This forms the creamy dressing.
Add the cooled macaroni to the dressing mixture, stirring gently to coat all the pasta evenly. Then fold in the chopped celery and diced bell pepper, ensuring even distribution of vegetables.
Taste the salad and adjust seasoning with additional salt and pepper as needed. Cover the bowl and refrigerate for at least 30 minutes to allow flavors to meld.
Before serving, give the salad a gentle toss and garnish with extra chopped vegetables if desired. Serve chilled with a fork.
