Mix together the fish sauce, soy sauce, kecap manis, oyster sauce and water in a bowl or jug and set aside.
Heat up a large drizzle of oil in a wok or stir-fry pan. Then stir-fry the green beans for a few minutes on a medium high heat. Add the chopped chilis and garlic and stir-fry for a couple more minutes. At this point, also start frying the eggs (if using).
Add the pork and break up with a wooden spoon. Stir-fry until cooked (an additional few minutes).
Pour in the sauce, stir well, then let bubble for a minute or two more.
Stir in the basil until wilted, then serve with the rice (and a fried egg, if desired).
