Boil the mung beans in about two cups of water for 10 minutes. Turn off the heat, cover the pan tightly and leave the mung beans to soak and swell for a couple of hours.
Heat about three tablespoonfuls of cooking oil in a pan and sauté the garlic, onion, chilis and tomato, stirring often, until the vegetables start to soften.
Add the pork bones to the pan and cook until no longer pink.
Add the mung beans with the cooking liquid. Stir well. Add more water to make a rather thin mixture.
Season with patis (fish sauce) and with freshly ground black pepper. Bring to the boil and simmer for about an hour or until the mung beans are mushy and the mixture has thickened. You will need to stir the pot every 15 minutes or so, scraping the bottom of the pan, to make sure that the mung beans do not settle and stick to the bottom.
Add the chunky vegetables, stir and simmer for 10 minutes.
Taste and adjust seasonings, if needed. Add the leafy vegetables and simmer for another five minutes.
Taste one last time and adjust seasonings, if needed. Ladle into bowls. Sprinkle the chicharon on top. Alternatively, add the chicharon along with the leafy vegetables and allow to boil into the stew. Your choice, really.