Place the chicken breasts in the bottom of the slow cooker. Add the diced onion, minced garlic, diced tomatoes with green chilies, and chicken broth.
Stir in the black beans, frozen corn, chili powder, cumin, cayenne pepper, salt, and black pepper until evenly combined.
Cover and cook on low for 6 to 7 hours, until the chicken reaches an internal temperature of 165°F and shreds easily.
Remove the chicken breasts, shred them with two forks, and return the meat to the slow cooker. Stir to mix everything together.
Ladle the soup into bowls and top each serving with tortilla strips, chopped cilantro, and a squeeze of lime.