Preheat oven to 200 degrees C. Place pork into a heavy baking dish and add enough water to cover bottom of the dish. Cover it with a tight fitting lid and cook until browned. You may need to add more water while it is cooking so be sure to check.
In a large pot, combine browned pork, chillies, potatoes, tomatoes, onion, celery, cumin, chillis and water. Simmer for 5 to 6 hours.
Remove bones from the soup, pull off any meat, and put meat back into soup. Serve with chopped fresh coriander on top, if desired.
If you want less heat, remove all seeds from the green chillies before chopping.