Bring a large pot of salted water to a rolling boil. Add elbow macaroni and cook for about 8-10 minutes, until al dente. Drain and rinse under cold water.

In a medium bowl, combine mayonnaise, sour cream, lime juice, taco seasoning, salt, and pepper. Whisk until smooth.

In a large bowl, add cooled macaroni, black beans, sweet corn, diced bell peppers, red onion, and cheddar cheese. If using cilantro, add it now. Mix gently.

Pour the dressing over the salad and fold gently until evenly coated.

Cover and refrigerate for at least 1 hour before serving to allow flavors to meld.

Before serving, stir gently, adjust seasonings, and serve chilled.