Frying involves cooking food in fat, usually butter or oil. Try to use a polyunsaturated oil like corn or safflower, and use only a little. This technique is called shallow- or panfrying. If you use a wok, even less oil is required. The food must be constantly moved round the pan, and vegetables require no more than 3 minutes. This is called stir-frying. Deep-frying is a technique used for such things as rissoles, and means that the food is submerged in hot oil and cooked until crisp.