Sweet and Sour Beef

In a wok, heat the oil and fry garlic until golden. Add the beef and fry until medium rare. Remove the beef slices and set aside. Add the onion, cucumber, tomato and chillies to the wok, stir-frying between each addition. Return the beef to the wok and heat through. Add sugar, soy sauce and white vinegar, stirring until sugar dissolves. Stir in the cornstarch, green onions and black pepper. Coo