Idli (ˈɪdliː, also romanized "idly" or "iddly", plural "idlis"; ; ; ; ; ) is a savory cake of south Indian

South Indian cuisine

South Indian Cuisine is a term used to refer to the cuisines found in the four southern states of India: Andhra Pradesh, Karnataka, Kerala and Tamil Nadu.-Similarities and differences in "Four states' cuisines":...

 origin popular throughout India

India

India , officially the Republic of India , is a country in South Asia. It is the seventh-largest country by geographical area, the second-most populous country with over 1.2 billion people, and the most populous democracy in the world...

. The cakes are usually two to three inches in diameter and are made by steaming a batter consisting of fermented

Fermentation (food)

Fermentation in food processing typically is the conversion of carbohydrates to alcohols and carbon dioxide or organic acids using yeasts, bacteria, or a combination thereof, under anaerobic conditions. Fermentation in simple terms is the chemical conversion of sugars into ethanol...

 black lentils

Urad (bean)

Vigna mungo, known as urad, urad dal, udad dal, urd bean, urd, urid, black matpe bean, black gram, black lentil [not to be confused with the much smaller true black lentil ], maas , đậu đen or white lentil, is a bean grown in southern Asia...

 (de-husked) and rice

Rice

Rice is the seed of the monocot plants Oryza sativa or Oryza glaberrima . As a cereal grain, it is the most important staple food for a large part of the world's human population, especially in East Asia, Southeast Asia, South Asia, the Middle East, and the West Indies...

. The fermentation process breaks down the starches so that they are more readily metabolized by the body. The earliest mention of idli in India occurs in Tamil sangam literature.