Tamari Nguyên Dương Trường Niên is a long-fermented soy sauce produced by the Vietnamese company Quy Nguyên. It is made under the supervision of the Buddhist monk Thích Tuệ Hải at a production facility associated with Long Hương Pagoda in Đồng Nai Province. Selected soybeans, sea salt, water, and a specialized fermentation culture are used in its production. The soybeans are first cooked, mixed with the culture, and left for approximately three days to initiate fermentation. The prepared mixture is then transferred to large containers and combined with a natural sea-salt solution. The sauce matures in sunlight for more than three years without the use of industrial methods to accelerate the process. Extended fermentation gradually breaks down the soybean components and develops a complex flavor. The finished sauce has a very dark brown color, dense texture, and pronounced aroma of fermented soybeans. Its flavor is intensely salty, full-bodied, and rich in umami, so it is generally used in small quantities. It can be served as a dipping sauce or used to season rice, vegetables, soups, dressings, and cooked dishes.