In a large pot, heat a little olive oil over medium heat.
Add diced onions and sauté until translucent, about 5 minutes.
Stir in minced garlic and cook for another minute.
Add shredded chicken, black beans, corn, diced tomatoes, and chicken broth.
Season with chili powder, cumin, salt, and pepper.
Bring the mixture to a boil, then reduce heat and simmer for 20 minutes.
Adjust seasoning to taste as needed.
While the soup simmers, prepare tortilla strips by frying or baking until crispy.
Once the soup is ready, ladle into bowls.
Top each bowl with crispy tortilla strips, avocado slices, and fresh cilantro before serving.