In your Dutch oven heat your olive oil over medium-high heat. Add the onion and garlic and cook until soft. Place your chicken breasts on top of your onion and garlic mixture and sprinkle all your spices over the chicken. Add both cans of tomatoes and the chicken stock and bring everything to a low boil.

Reduce the heat and cook at a simmer for 2 hours. Your chicken should become tender and start to fall apart. At that point take two forks and carefully shred your chicken. Stir the shredded chicken in the remaining spiced juices and continue to cook on low for another 45 minutes.

Fill your tortillas with the shredded chicken mixture and top with all of your favorites.