Bring a large pot of salted water to a boil and cook the pasta according to package directions until al dente. Drain the pasta thoroughly and spread it on a sheet pan to cool slightly while you prepare the other components. I like to rinse pasta with cool water after draining to stop the cooking process and prevent it from becoming mushy when mixed with the creamy dressing.

In a large mixing bowl, whisk together the mayonnaise and sour cream until smooth and combined. Add the finely minced chipotle peppers, lime juice, garlic powder, salt, pepper, and ground cumin. Whisk everything together until the dressing is uniform in color with no streaks of white—this should take about 1-2 minutes. Taste the dressing and adjust the seasoning if needed; the chipotle peppers can vary in spice level, so you may want more or less depending on your heat preference.

Add the cooled pasta from Step 1 to the dressing bowl and toss until every strand is coated. Add the diced red onion, rinsed black beans, corn, and tomatoes to the pasta. Toss everything together gently but thoroughly, making sure the dressing coats all the ingredients evenly. Fold in the cooked chicken pieces carefully to distribute them throughout the salad without breaking them apart.

Just before serving, gently fold in the diced avocado to prevent it from breaking down and becoming mushy. Scatter the fresh cilantro over the top and give the salad one final gentle toss. I always add the avocado at the very last moment before serving rather than mixing it in earlier, as it becomes discolored and loses its texture when exposed to the acidic lime dressing for too long.