Start off by seasoning your chicken on both sides with half of the salt and pepper. If your using bone in chicken cut off skin before seasoning your chicken. Fill a pot with the water and start to boil.
Pour Oil into a frying pan and start browning chicken on both sides about 4 minute on each side. You might want to fry only 4 or 5 at a time for an even color. Remember you not cooking the chicken all the way just browning.
The pot of water should be boiling at this time, put the tomatillos and jalapenos into the boiling water and boil 12-15 minutes.
While the tomatillos and jalapenos are boiling finish browning all of the chicken.
Once the tomatillos and jalapenos are ready drain the water and put the tomatillos, jalapenos, cilantro, garlic, and the chicken broth into a blender and start pulsing until all the ingredients are all mixed and then blend for 30-40 seconds. Once blended leave in blender until needed.
Pour the remaining oil in a pot (pot should be a good size one you would use for soups) and start frying the onion on med-high heat. After about two minutes put the rest of the salt, pepper, cumin, and cayenne pepper and fry for an additional 5 minutes, add the browned chicken and pour the tomatillo mixture and simmer for 20 minutes.
Take out the chicken with tongs and put in to a bowl and start shredding. Once chicken is shredded place back into pot and simmer for another 20 minutes.
Note: You do not need to do the last step if you are using boneless chicken just simmer until chicken in fork tender and stir it and the chicken should fall apart. I like to use bone in chicken because I feel it has more falvor than boneless chicken.