Heat the oil in a wok or frying pan.
Add the chopped pork. Cook over high heat, stirring occasionally, until browned.
Add the onion, garlic, ginger, tomatoes and chilis. Season with patis. Saute just until the vegetables start to soften.
Add the green beans. Pour in the coconut milk. Taste and add more patis.
Boil over medium heat, uncovered (to avoid curdling) and with occasional stirring, for about five minutes or until the green beans are done and the mixture is almost dry.
Pour in the coconut cream. Adjust the seasoning once more. Boil gently, still uncovered, for about two minutes.