4 boneless chicken breast halves
1/2 medium onion, sliced
2 garlic cloves, smashed
1 tablespoon salt
2 tablespoons butter
1 garlic clove, minced
1/2 medium onion, chopped
1 medium tomato, seeded and chopped
1/2 green bell pepper, chopped
1 teaspoon fresh coarse ground black pepper
1 teaspoon marjoram
1/4 cup cilantro, chopped (or to taste)
1 1/2 teaspoons ground cumin
2 tablespoons tomato sauce
1 1/2 teaspoons salt (to taste)
1/2 cup chicken broth (reserved)

1  Place first four ingredients in a pot. Add just enough water to cover the chicken.
2  Bring to a slow boil, cover, lower heat to maintain a simmer and cook until done, about 20 – 25 minutes. If using a whole chicken; cook approximately 50 – 60 minutes.
3  Remove chicken from pot, let cool and shred. (I cool my chicken in the refrigerator to be safe) If using a whole chicken; remove meat from bones and shred. Reserve broth.
4  In a large pan, melt butter over low heat.
5  Add the remaining ingredients listed, except tomato sauce, salt, and broth.
6 Sauté until soft, about 10 minutes.
7  Stir in shredded chicken and briefly sauté.
8 Add tomato sauce and ½ cup of reserved broth.
9  Salt to taste.

source:    http://www.food.com/recipe/shredded-chicken-for-enchiladas-tostadas-tacos-169500