Add chicken broth, tomatoes/chilis, corn, cilantro, salt and pepper to dutch oven and bring to a boil.
Simmer for 30 minutes.
Add chicken and simmer an additional 30 minutes.
Add broken tortilla chips to bowl. (This is a great way to use up the broken pieces in the bottom of a bag of chips.) Pour soup over chips to soften. Top with cheese, avocado and sour cream if desired.