Drain and rinse your beans.
Light 18 charcoal briquettes in a chimney starter or barbecue pit. Once they've fully lit (the coals are white) place them, evenly spaced, underneath your cast iron dutch oven. Pour the cooking oil into the dutch oven and heat until shimmering. Add the diced onions and saute until translucent and starting to brown.
Add the chicken stock, beans, pork hocks, black pepper, garlic, bay leaves, and cayenne pepper to the pot and stir thoroughly. Cover and bring to a boil.
Once the pot has come to a boil, remove enough charcoal to leave about 8-10 underneath the dutch oven to bring it down to a simmer (depending on weather conditions - see above). Simmer covered, for 1 hour, replacing the coals as necessary to maintain the simmer (about every 30 minutes, or so).
Remove the pork hocks from the beans to a cutting board. Cut the meat and skin off the bones. Discard the bones and skin (if desired - I dice the skin and put it back in). Dice up the meat and stir it back into the pot.
Add the diced green chiles to the pot, then smash about 1/2 a cup of the beans up against the side of the pot and stir them back in (this will make the broth creamy). Cover and simmer for at least another 30 minutes, or until the beans are tender. If the broth appears too thick, add more stock. If it's too thin, add enough hot coals underneath to bring back to a boil, uncover and let reduce to the desired consistency.
Add salt to taste and serve.