
Cook the chicken. Add the chicken to a pot with the salt, pepper, bay leaf and enough water to cover. Bring to a simmer and cook for 15 to 20 minutes, until the chicken is cooked through. Remove the chicken and shred with forks. Reserve about ½ cup of the cooking liquid.
Sauté the onion. In a large skillet, heat the oil over medium heat. Add the onion and cook for 8 to 10 minutes, until soft and lightly caramelized. Add the garlic and stir for another 30 seconds.
Make the tinga sauce. While the onions are sautéing, add the tomatoes, chipotle peppers, adobo sauce, oregano, cumin, and chicken broth to a high-powered blender. Blend until smooth. Pour the sauce into the skillet with the onions and garlic and simmer for 5 to 7 minutes.
Combine the chicken and sauce. Add the shredded chicken to the skillet and toss well to combine. Simmer for another 5 minutes, until the chicken absorbs the smoky tomato-chipotle flavor, then serve.