Place the meat, half an onion, 1 garlic clove, and bay leaves in a large pot of water. Cook over high heat until it comes to boil, then cover the pot and reduce the heat to a simmer. Let it cook for about two hours.
Boil approximately one and a half cups of water, cut the tops of the chillies, remove the seeds and add to the boiling water to hydrate for about 10 minutes.
Once the meat is ready, put it in a bowl and shred it with the help of two forks, here you can remove the fat from the meat if you want. Strain and save some of the broth that you used to cook the meat.
Wash and cut the tomatoes into quarters and blend them with one garlic clove, half an onion, a pinch of Mexican oregano, about one cup of the broth from the meat that we put aside, the hydrated guajillo chillies and pepper to taste.
Heat a little vegetable oil in a pan over medium heat, add the meat, salsa and salt to taste, lower the heat and cook for another 5 minutes stirring constantly.
Reheat the tortillas and fill them with the stew to serve as a taco.