Soak the tangerine peel in cold water for about 2 hours or until soft. Drain and slice into strips about 5mm (1⁄5 inch) wide.

Peel the orange rind lengthwise and blanch in boiling water for 5 minutes to remove its bitterness. Drain and rinse in cold water. Slice into strips similar to the tangerine strips.

Cut the beef into thickish slices, about 2.5 x 4cm (1 x 1½ inches) and put into a bowl.

Prepare the marinade: add the salt, sugar, soy sauces, wine or sherry and potato flour to the meat. Add the water, 15ml (1tbsp) at a time, and stir in the same direction until all is absorbed. Mix in the chopped chilli and leave to marinate for 30–60 minutes.Blend in the hot chilli oil.

Heat a wok over a high heat until smoke rises. Add the oil and swirl it around. Add the ginger, stir, then add the white spring onion and let it sizzle. Add the tangerine and orange peel and fry for a few seconds. Put in the beef and, sliding the wok scoop or metal spatula to the bottom of the wok, flip and turn for 1–2 minutes or until very hot. Splash in the wine or sherry around the side of the wok, continuing to stir. When the sizzling dies down, add the chilli sauce. Cover, lower the heat and cook for about 2 minutes so that the flavour of the tangerine peel can permeate the beef.

Prepare the sauce: mix together the potato flour, water or stock and soy sauce.

Dribble the sauce into the wok and stir as the sauce thickens. Add the green spring onion and stir to mix. Remove to a warm serving dish. Serve immediately.