Like most present day Latin Americans, the Incas and their ancestors depended on boiled beans (frijoles) for much of their nourishment. Many lived so high in the mountains, however, that they couldn't cook ordinary dry beans—water boils at too low a temperature up there.1 To circumvent this, they used a remarkable bean known as the nuña.
Nuñas (pronounced noon-yas) are a type of the common bean (Phaseolus vulgaris); they are roughly the bean counterpart of popcorn. Heated with a little oil, nuñas burst out of their seed coats. The effect is less dramatic than popping popcorn—nuñas don't fly in the air; they open like small butterflies spreading their wings.2 The resulting product is soft and tastes somewhat like roasted peanuts.
Nuñas look much like common beans, but they are hard shelled. They come in many striking colors and patterns: white, red, and black-spotted, for instance. During cooking, the heat and moisture build up steam inside, and the hard hell and round shape mean that it can escape only by bursting out.
From Ecuador to southern Peru, nuñas are grown above 2,500 m altitude. They are produced mainly for home consumption and are much more common in houses than in markets. Nonetheless, they are often sold as part of a mixture of beans to be incorporated into soups.
That nuñas are unknown outside the Andes seems surprising. For industrialized nations, these popping beans could be a new and nutritious snack food. For developing nations, they could be a tasty source of high-quality protein. Toasting nuñas requires far less fuel than boiling beans, an important economic (and environmental) consideration in regions where fuel is scarce. In addition to having nutritional and energy-saving attributes, the plant is a nitrogen-fixing