Heat the cooking oil in a wok. Add the minced pork and stir fry just until the meat is no longer pink.
Add the ginger and lemongrass, and a splash of fish sauce. Cook until the meat has soaked up the fish sauce.
Pour in the broth. Bring to the boil, cover and simmer for about 10 minutes. That's all the time that minced pork needs to cook.
Add the liver to the wok. Season with a little more fish sauce. Turn up the heat to medium and continue cooking just until the liver is done and the mixture is almost dry.
Cool the meat. This is essential because you don't want the fresh herbs to wither in the heat when added to the meat.
When the meat has cooled, toss with the mint, cilantro, scallions, onion, chilies, lemon or lime juice and sugar.
Optionally top with crisp onion slices before serving.