Place the pork in a bowl, add the ginger, black pepper, fish sauce and sesame seed oil. Mix thoroughly.
Rinse the spinach and drain. If you’re using the stems, roughly chop so that you get bite size pieces.
Heat the cooking oil in a pan. When smoking hot, add the pork and cook, stirring, until the meat changes color.
Pour in some soy sauce (a tablespoon at this point should be enough) and continue stir frying until the mixture is almost dry.
Add the onion slices and the chilies, stir fry for another 30 seconds, then add the spinach and baby corn. Stir fry just until the spinach wilts and the baby corn pieces are heated through.
Taste the dish, add more fish sauce or soy sauce, if needed.