Gyros or gyro from Greek: γύρος [ˈʝiros] 'turn') is a Greek dish, consisting of meat, tomato, onion, and tzatziki sauce, and is served with pita bread. Gyros may also refer to the sandwich, which consists of the same ingredients.
To make gyros, pieces of meat are placed on a tall vertical spit, which turns in front of a source of heat, usually an electric broiler. If the meat is not fatty enough, strips of fat are added so that the roasting meat remains always moist and crispy at the same time. The rate of roasting can be adjusted by varying the strength of the heat and the distance between the heat and the meat, allowing the cook to adjust to varying rates of consumption. The outside of the meat is sliced vertically in thin, crispy shavings when done. It is generally served in an oiled, lightly grilled piece of pita, rolled up with various salads and sauces. The pita and gyro themselves are the only obligate ingredients; the remaining condiments to be added always being at the discretion of the customer, even down to the amount of salt and pepper used. An order of ap' óla, with everything, means that every available add-on is to be included, including generous peppering with red paprika. (source Wikipedia).