Heat up a large, flat-bottomed pan and add the olive oil, then add the sliced onion and bell peppers. Sauté for 5-10 minutes, until they are softened.
Remove the leaves from the fresh coriander and set them aside. Chop the coriander stalks and add to the pan along with the garlic, paprika, cumin, and chili powder. Cook for 1-2 minutes, until fragrant.
Add to the pan the tin of chopped tomatoes, the tomato puree, the chicken stock, and the cinnamon stick.
Nestle the chicken thighs into the pan and simmer, covered, on a low heat for 45 minutes, until the chicken is cooked through.
Using a fork, gently remove the chicken meat from the bones. Remove the bones from the pan.
Add the tin of black beans with the liquid, the drained kidney beans, and the dark chocolate. Stir everything together and then leave to simmer for another 5 minutes. Season to taste with salt and pepper.
Serve as desired, optionally with avocado, sour cream, or with rice.