For the dressing
, sour cream
, mustard, vinegar and sugar
together in a small bowl or glass measuring cup. Season with salt and pepper.
For the pasta: In a large mixing bowl, combine the macaroni
, bell pepper and red onion
the dressing over the salad and toss to combine. Season with salt and pepper. Serve immediately or keep up to 2 days in the refrigerator until ready to serve.