Cook the pork. Cover meats with water about 8 quarts. Add 1/4 cup salt and one large head of garlic cut through the equator, no need to peel. Bring to a boil, reduce to simmer. Skim off foam and simmer, covered for about 3 hours, until tender. Check from time to time, you may need more water. Cool slightly, then remove the meat. When ready to handle pull meat off bones, discard all bones, fat and skin. You can scoop out the onions and add to the pulled meat along with the garlic head. Squeeze out the pulp from the head of garlic and smash it with a fork, add it to the meat along with the onions, discard the paper skin from the garlic.
Refrigerate the broth. At serving time scoop off the fat from the broth (it will be very gelatinous ) add 1/4 cup ground chili d arbor to broth along with the corn. Bring to a boil then simmer. Taste for salt.