About a week of fermentation in a warm earthenware jar turns wilted mustard and radish leaves into a sharp, shelf-stable staple that can outlast an entire winter without refrigeration.
Gundruk is made by wilting mustard, radish or cauliflower leaves, packing them tightly into an earthenware jar with a little warm water, and letting them ferment for about a week before sun-drying. It's simmered into a sour soup or fried into a tangy side dish, a pantry staple across Nepal's high trans-Himalayan trade villages, including the Thakali homeland around Mustang where fresh greens are scarce much of the year.