Add the onions and cook, stirring occasionally until the onions are soft and translucent, about 5 minutes. Add the garlic and cook until fragrant, about 1 minute more. Add the chipotles, bay leaves, cumin, oregano, coriander, and cloves. Cook, stirring constantly for 1 minute more, until fragrant. Add the chicken stock, vinegar, and fish sauce. Bring to a boil and then add the beef back. Cover the pot with a lid and transfer to the oven. Cook at 250ºF for 2 1/2-3 hours, or until completely tender.