Preheat the wok or a cast-iron pan until it starts to smoke lightly. Add in sunflower oil, along with the minced ginger and diced onion. Cook over medium heat until the onions soften. Add in the ground pork and turn up the heat, stirring to break up any large chunks. Cook until all the pork turns pale and opaque–there is no need to brown or crisp the meat.

Add wine, dark soy sauce, hoisin, sugar and sesame oil. With the heat on high, stir everything together until well-combined. Taste the filling and adjust the seasoning if needed.

Cook for a couple of more minutes to cook off any remaining liquid. Stir in the cornflour and water mixture, allowing everything to bubble together for 30 seconds to a minute. Turn off the heat and let the filling cool uncovered. After the filling has cooled, mix in the chopped spring onions.