In a large pot, sauté the chopped onion and garlic over medium heat until translucent.
Add the diced chicken and cook until browned on all sides.
Stir in the green bell pepper and cook for another 2-3 minutes.
Add the cooked white beans and mix well.
Pour in the chicken broth and bring to a boil.
Reduce heat and let it simmer for 15 minutes.
Stir in the sour cream and spices (cumin, oregano, salt, and pepper).
Simmer for an additional 5 minutes, stirring occasionally.
Top with shredded cheese and let it melt slightly.
Garnish with fresh cilantro before serving.