Season the chicken with salt and pepper. Set aside.
In a large saucepan, heat the oil over medium heat. Cook the onion and garlic until transparent and fragrant, around 4 minutes.
Add in the chili powder, oregano, broth, diced tomatoes and tomato paste. Mix to combine and bring to a boil.
Add in the chicken. Lower the heat and allow to simmer for 10-15 minutes, or until the chicken is cooked. Shred the chicken using two forks.
Add in the black beans and corn. Season with more salt and pepper to taste. Simmer for around 10 minutes, or until heated.
Serve in bowls topped with crushed tortilla chips and sour cream, if using.