Put them in a bowl.

 Leave to marinate for 20 mins.

2)Heat a wok until it is very hot, then add the groundnut oil.

When it is slightly smoking, add the beef slices and stir-fry for 5 mins or until lightly browned.

Remove the meat from the wok and drain well in a colander set inside a bowl.

Discard the drained oil.


3)Wipe the wok clean and reheat it over a high heat.

Add the peppers, and cook for 3-4 mins or until softened.

Add the oyster sauce and bring it to a simmer.

Return the drained beef slices to the wok and toss them thoroughly with the oyster sauce.

Turn the mixture on to a serving platter, top with the spring onions and serve immediately.