Rub roast with salt, cumin, pepper, mexican oregano add quartered onion to large pot and add chicken broth and enough water to just cover. Place a lid on and bring to boil. Reduce to simmer for 2 hours until or until it is very tender and pulls apart easily with forks
Place roast in a oven proof baking pan, ( I use stoneware) no lid and roast in a hot oven (400 degrees) with about 2 cups of the broth it cooked in until the roast is brown and crusty on top about an hour. Pull out of oven, pull meat apart and serve with warm tortillas and your choice of toppings.