In a small pot over medium heat, add the chicken broth, chicken, and spices. Bring to a simmer.
While the chicken is warming, dice the onion and add it to the pot.
Chop the tomatillo into 1/4-inch pieces and add it to the pot, stirring well. Cover and allow to simmer for 10 minutes.
Add black beans and chilis, then remove from the heat.
Chop cilantro and add to the soup as a garnish. Serve and enjoy!