Bring a pot of salty water to a boil and add the chicken breast to cook. Add the onion cut in quarters, garlic cloves, bay leaves, oregano, and salt. If you use chicken stock, go easy on salt. Let the chicken simmer until it is cooked through. It could take between 12-15 minutes.

Make sure you skim the foam that forms on top of the water as it starts boiling. When the chicken is cooked, set aside.

While the chicken is cooking, place the tomatoes in a medium saucepan, cover with water, bring to a simmer over medium-high heat and cook for 8 to 10 minutes, or until the tomatoes are soft and mushy but not falling apart. Note: If you use canned tomatoes, skip this step.

In a blender, place the tomatoes (or the can of crushed tomatoes if you use one), salt, pepper, and 2-3 chiles from the can.

After blending the ingredients, taste for salt and pepper and adjust if necessary.

Slice the onions and garlic cloves thinly. Heat the oil in a large pan(skillet) and add the onion and garlic. Cook until the onions are soft and translucent, about 5-6 minutes.

Pour the salsa over onions. Add oregano, marjoram, thyme, and pepper. (Be careful as the sauce will steam and bubble).

Simmer the sauce, occasionally stirring, until the sauce deepens in color, becomes darker and less soupy, about 7-8 minutes.

Take the chicken out of the broth, and with two forks, shred the meat.

Add it to the sauce and mix well to incorporate the chicken.

Let it simmer for only a minute and serve over rice or on warm tortillas.