Place the oyster sauce and cornflour into a bowl and stir well to combine. Add the beef strips to the marinade and mix well to coat the beef in the marinade. Set aside and carry on preparing the rest of the vegetables for the dish.
Heat a wok over a high heat and pour the sunflower oil into the pan. Cook the steak strips in 2 batches so you don't overcrowd the pan. Cook for a minute on each side and remove from the wok onto a plate and set aside.
Add more sunflower oil into the pan if necessary and add the onion, green and red peppers to the pan or wok and stir-fry for 2 minutes. Next add the garlic, chilli and ginger to the mix and stir fry for a further minute.
Next pour in the Shaoxing rice wine, dark and light soy sauces and water and continue to stir fry for a further 2 minutes.
Spoon in the black bean sauce and return the steak strips to the wok. Stir fry for a minute to heat everything. Serve and garnish with sliced spring onions.
This recipe uses lean rump steak, however you can substitute with any quick fry steak cut. Sirloin, ribeye and fillet would work equally well in this dish. However, do not replace with a stewing cut as those cuts require a longer cooking time.If you cannot find Shaoxing rice wine then use dry sherry or even a little white wine in the dish.If you do not have a wok, use a large non-stick frying pan instead.