Heat olive oil in a large pot over medium heat.
Add chopped onions and sauté until translucent.
Stir in minced garlic and cook for another minute.
Add diced bell peppers and cook until softened.
Incorporate shredded cooked chicken into the pot.
Pour in chicken broth and diced tomatoes with green chilies.
Season with cumin, chili powder, and salt to taste.
Bring to a boil, then reduce heat and simmer for 20 minutes.
Stir in corn and black beans for the last 5 minutes of cooking.
Serve hot, garnished with cheese, cilantro, and avocado.