Umu

An earth oven, ground oven or cooking pit is one of the simplest and most ancient cooking structures. The earliest known earth oven was discovered in Central Europe and dated to 29,000 BC. At its most basic, an earth oven is a pit in the ground used to trap heat and bake, smoke, or steam food. Earth ovens have been used in many places and cultures in the past, and the presence of such cooking pits is a key sign of human settlement often sought by archaeologists. Earth ovens remain a common tool for cooking large quantities of food where no equipment is available.[citation needed] They have been used in various civilizations around the world and are still commonly found in the Pacific region to date. To bake food, the fire is built, then allowed to burn down to a smoulder. The food is then placed in the oven and covered. This covered area can be used to bake bread or other various items. Steaming food in an earth oven covers a similar process. Fire-heated rocks are put into a pit and are covered with green vegetation to add moisture and large quantities of food. More green vegetation and sometimes water are then added, if more moisture is needed. Finally, a covering of earth is added over everything. The food in the pit can take up to several hours to a full day to cook, regardless of the dry or wet method used. Today, many communities still use cooking pits for ceremonial or celebratory occasions, including the indigenous Fijian lovo, the Hawaiian imu, the Māori hāngī, the Mexican barbacoa, and the New England clambake.[citation needed] The central Asian tandoor use the method primarily for uncovered, live-fire baking, which is a transitional design between the earth oven and the horizontal-plan masonry oven. This method is essentially a permanent earth oven made out of clay or firebrick with a constantly burning, very hot fire in the bottom.

Source: Wikipedia