Combine chicken, chicken broth, diced tomatoes with their juices, jicama, onion, corn, peas, celery, squash, salt, pepper, and cayenne pepper in a large pot or Dutch oven. Bring to a low boil over medium-high heat; reduce heat to low and simmer for about 15 minutes. Adjust spices to personal taste if needed.
Add sour cream to the soup and continue simmering until heated through, about 10 minutes.
