A clay oven, most often called a tandoor, is a cylindrical clay, brick, or stone oven with a domed top, heated from below or the sides to very high temperatures - commonly cited up to about 900°F (480°C) - using wood or charcoal. Food cooks from the direct heat of the clay walls plus the convection currents inside the chamber, which sears the surface quickly while keeping the inside moist.
This intense, dry heat gives tandoor-cooked dishes their characteristic charred, smoky exterior, and it's why the oven works especially well for flatbreads like naan slapped directly onto the hot inner wall, as well as skewered meats such as tandoori chicken and kebabs.
Clay ovens have long been central to cooking in the Middle East, Central Asia, and the Indian subcontinent, and modern versions built with steel or ceramic linings are now common in restaurants outside those regions as well.