To make chuño potatoes are left out on the ground at high altitudes in the coldest winter months. They alternately freeze in the sub zero nights and dehydrate during the day in the strong, harsh high altitude sun. The process takes a couple of weeks; when completed the fully dehydrated potatoes can be stored for long periods, sometimes up to several years. These potatoes are ready for storage - the skin has pretty much dried out completely and is flaking off the potatos which have turned black inside.