Put the pork strips on a plate and sprinkle them with salt, pepper and cornflour (cornstarch), rubbing them into the meat with your fingers. Heat the oil in a large frying-pan. Add the pork and stir-fry over high heat for 3 minutes. Push the pork to the side of the pan and add the greens or cabbage and vegetable fat. Mix the greens or cabbage with the remainder of the oil and the fat. Reduce the heat to moderate and stir in the stock, soy sauce and sugar. Fry the greens or cabbage, turning constantly, for3 minutes.

Stir the pork strips into the vegetables, mixing until they are well blended. Pour the wine or sherry over the mixture and stir-fry for a further 1 minute.

Remove from the heat and transfer the mixture to a warm serving dish. Serve at once.