When a dough of wheat flour and water is heated quickly, the dough puffs up because of steam pressure. The simplest unleavened bread was made by soaking grain in cold water until soft and sticky, forming thin cakes, and baking on a slab of wood before a hot fire. A similar procedure can be used for any cracked grain or meal. In the middle East today, coarse flour and water are mixed, kneaded, rolled to 1/16 in. thick, and baked on a steel bowl placed upside down in the embers.