Heat the oil in a large Dutch oven or other heavy-bottomed pot over medium heat. Add the onion, pepper and garlic and stir to coat with the oil. Season the vegetables with salt and pepper and cook, stirring occasionally, until softened, 4-5 minutes. Add the turkey and cook until browned, breaking it up as it cooks. Stir in the chipotles, adobo sauce, cumin, oregano, 1 teaspoon salt and ½ teaspoon black pepper. Then add the beans, pumpkin, tomatoes, and chicken stock and stir to combine well.