In a large heavy bottom pot, heat the vegetable oil over medium-high heat until it shimmers.
Sprinkle the chicken breasts with salt, and place skin side down into the pot.
Brown for 5 minutes until skin has turned golden brown in color, flip and cook for another 5 minutes.
Transfer the breasts to a plate or cutting board.
Reduce the heat to medium and add the onion, chopped fresh tomatoes, jalapeño and pinch of salt, and cook, stirring occasionally, until softened, about 8 minutes.
Add garlic, oregano, cinnamon and cumin, and stir constantly for about 30 seconds.
Add the chicken stock, bay leaves, canned tomatoes and reserved chicken and any juices.
Bring to a boil, then lower heat to medium, cover and simmer until the chicken is cooked through, about 30 minutes.
Transfer the chicken breast to a plate or cutting board and turn the heat to high, bringing the sauce to a boil and stirring occasionally for about 20 minutes until the sauce is reduced to a thick consistency.
Once the chicken is cool enough to handle, shred it with two forks, trying to get long thin shreds of meat. (Discard the skin if you like.)
Discard the bay leaves and return the chicken to the sauce.
Lower the heat, stir in the vinegar, and simmer for 15 minutes.
To assemble tacos, start with a scoop of chicken, followed by queso fresco, pickled jalapeños and cilantro.