Place the meat slices in a bowl, add the soy sauce, rice wine or sherry and cornflour and mix well.
Heat a wok or large frying pan and add the oil. When hot, add the beef and stir fry for 2 minutes to brown. Using a slotted spoon, remove beef and set aside.
Add the onions to the wok and stir fry for 1 minute. Pour in two tablespoons of water and cook