Chuño
On the Altiplano around Lake Titicaca, in June and July when the nights drop to -10 °C and the days are bright and dry, Aymara and Quechua families spread small, bitter potatoes on the grass to make chuño, a technique far older than the Inca. The potatoes freeze at night and thaw in the sun for several days, then are trodden barefoot to squeeze out the water and rub off the skins, and dried for a couple of weeks more. The result is light, wrinkled, grey-black chuño negro that keeps for years; soaked in running stream water instead, the same potatoes become white tunta. Rehydrated and boiled, chuño is firm, slightly chewy and spongy, with an earthy, faintly mineral, almost fermented taste; it goes into chairo soup, into chuño phuti, or beside grilled meat with spicy llajwa. Skipping the long soak is the big mistake: it stays bitter and gritty, so soak it for at least 12 hours, changing the water. Dried chuño is ready when it is rock hard, very light and rattles in a bag. Chef's tip: without Andean frosts, a freezer and a low oven make a fair version; the method is below.
Paraguayan