Heat the olive oil in a large pot over medium heat and sauté the onion, garlic, and bell pepper until they are soft and fragrant.
Add the chicken breast, chicken broth, diced tomatoes, black beans, corn, chili powder, cumin, salt, and pepper to the pot.
Bring the liquid to a gentle boil, then reduce the heat and simmer for 20 minutes until the chicken is fully cooked through.
Remove the chicken breast from the soup, shred it using two forks, and then stir the shredded meat back into the pot.
While the soup finishes, slice the corn tortilla into thin strips and toast them in a dry skillet until they are golden and crisp.
Stir the fresh lime juice into the soup to brighten the flavors before ladling it into a serving bowl.
Garnish the soup with the fresh avocado slices, cilantro, and the toasted tortilla strips.