Chuño (spanish pronunciation: [ˈtʃuɲo]) 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 bolivia, peru, chile and northwest argentina. it is a five-day process, obtained by exposing a bitter, 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). the word comes from quechua ch'uñu, meaning 'frozen potato' ('wrinkled' in the dialects of the junín region).

Source: Wikipedia