Chuño is a freeze-dried potato product traditionally made by Quechua and Aymara communities of Bolivia and Peru, and is known in various countries of South America, including Argentina, Bolivia, Chile and Peru. It is a five-day process, obtained by exposing a frost-resistant variety of potatoes to the very low night temperatures of the Andean Altiplano, freezing them, and subsequently exposing them to the intense sunlight of the day (this being the traditional process). (source)