Place half of the sherry or rice wine and soy sauce in a shallow non-metallic dish and add the sesame oil and cornflour. Stir in the beef and set aside for 15 minutes (or up to 24 hours, covered with clingfilm in the fridge).
Heat a wok until searing hot. Place the remaining tablespoon of sherry and soy sauce in a small pan with the chicken stock, then bring to a simmer. Add half the sunflower oil and swirl it up the sides of the wok. Tip in the beef and stir-fry for 3-4 minutes until well sealed and lightly golden. Transfer to a plate.
Add the rest of the sunflower oil to the wok. Add the ginger and stir-fry for 10 seconds. Tip in the greens and continue to stir-fry for 2-3 minutes until heated through and any leaves are just beginning to wilt, splashing over a little water occasionally to help the greens cook.
Return the beef to the wok, then stir in the hot stock mixture. Cook for another minute or so until bubbling, stirring. Spoon the steamed rice into warmed large Oriental-style bowls and spoon the ginger beef and greens on top. Scatter over the spring onions and chilli to serve.