After each heavy rain, Ninh Binh locals seek out a unique delicacy that emerges between the mountain rocks - rock moss, locally known as "dun da." This moss, which thrives on rain-soaked limestone formations, has been a traditional specialty of Ninh Binh for generations.

"Dun da," or stone moss, resembles jelly-like, translucent green mushrooms. The plant only appears after rains during the summer, thriving on damp crevices in the region’s white limestone mountains. Historically, when resources were scarce, locals would climb mountains to harvest this moss to supplement their diet. Today, it’s a sought-after delicacy.

Local resident Yen Nhi shares that gathering rock moss can be dangerous due to its growth on steep mountain sides and its brief availability after heavy rain. "It must be harvested right after rainfall," she explains, "because as soon as the weather dries, the moss withers and becomes unusable."

The preparation of dun da is a meticulous process. Nhi describes it as a delicate material akin to jelly, covered in dust and leaves due to its exposure on rocks. The moss must be thoroughly washed, often soaked in rice water and rinsed multiple times to remove impurities, before it can be cooked. The simplest, most traditional dish is boiled dun, served with a peanut salt dip.

"Boiling dun and dipping it in peanut salt preserves the pure taste while being quick and easy," Nhi adds, describing the traditional Ninh Binh method of preparation.

While boiled dun is the most popular, the moss has inspired other creative dishes such as stir-fried dun, dun salad with shrimp and pork, and a sour pickled version. However, one of the most beloved variations is the crab soup with dun. According to Nhi, many visitors come specifically to try this dish, where the moss is blanched and served with a rich crab broth made from natural freshwater crabs, tomatoes, meatballs, and tofu. The blend of fresh moss and crab paste creates a flavorful, tangy, and cooling dish.

The unique nature of rock moss - its seasonal availability and refreshingly cool taste - makes it a prized specialty of Ninh Binh’s limestone mountains. Outside of the summer months, when it’s no longer readily available, even high-paying visitors may struggle to find it. In peak season from June to August, fresh dun can sell for about 20,000–30,000 VND per kilogram, rising to 35,000–40,000 VND off-season.

To meet demand year-round, locals also prepare dried dun, which can be preserved and transported. Producing dried dun is labor-intensive, requiring 3–4 kilograms of fresh moss to yield one kilogram of dried product, which sells for 90,000–100,000 VND depending on the season and location.

With its light, refreshing qualities, rock moss has become a perfect summer delicacy that captivates both locals and visitors to Ninh Binh, a true taste of its rugged limestone landscape.

Ngoc Vi