In a Dutch oven or large soup pot, heat 1 table over medium heat. Add the chicken and sauté for about 5 minutes, or until browned. Using slotted spoon, transfer to a plate and reserve.

Add the remaining 1 tablespoon olive oil to the pot over medium heat. Add the onion and garlic and sauté for about three minutes, until the onion is translucent. Stir in the bell pepper and sauté for 3 minutes more, or until the bell pepper is is soft. Add the tomato and return the chicken to the pot. Stir in the chili powder, cumin, and oregano to coat all the ingredients. Add the chicken stock, beans, and salt and bring the liquid to a boil. Decrease the heat to medium and simmer uncovered, stirring occasionally, for 20 to 25 minutes, until the chili thickens to a stew-like consistency. 

Ladle the chili into soup bowls. Garnish each serving with 1 tablespoons of the sour cream and a scattering of green onion. Serve at once.