Hai Duong green bean cakes have been famous for more than a century, and are closely associated with a story about Bao Dai- Vietnam’s last emperor. The story is that one day King Bao Dai visited Hai Duong province, where he was offered a cake made of green bean, sugar and fat. The King liked the cake and its subtle flavor finely blended with green tea. He rewarded the Hai Duong green bean cake by allowing the local people to print “Golden Dragon” - a symbol of royal power - on the packaging of the cake, giving them a label that distinguishes them from products from elsewhere. Nguyen Dinh Giang is Vice President of the Hai Duong Green Bean Cake Association: “Following national reunification in 1975, the people of Hai Duong revived the craft of making green bean cakes. Since 1980, there have been 80 producers. We inherited local secrets to retain the original flavor of the cake and applied new technology in production to preserve it up to one year instead of one or two weeks”.

Actually, the recipe for green bean cake is not complicated. Luong Xuan Hat of the Gia Bao Green Bean Cake Company says green bean, sugar, fat, or vegetable oil, grapefruit flower essence, and coconut essence should be carefully prepared and mixed in a certain ratio. Otherwise the cake completely loses its flavor. Hat said: "Ingredients need to be carefully managed and have certificates of origin and quality. The green beans must be ripe and quite yellow inside. The green beans are roasted, finely ground, and mixed with the other ingredients”.

Hai Duong green bean cakes have been exported to a number of countries around the world. Mr. Giang again: “We have applied new technology to improve the quality of our green bean cakes. Our workers are trained in food safety. We have improved our packaging and diversified our products to meet market demand. We sell green bean powder and fried soybean”.

No one misses an opportunity to buy some green bean cakes whenever they pass through Hai Duong province. Tran Manh Ha, who currently works in Taiwan, China said: "I often buy green bean cakes as gifts for my family and friends in Taiwan. People there ask me to bring them some. Although there are a lot of confectionaries in Taiwan, people still like these cakes for their special taste”.

There are more than 50 brands of green bean cakes in Hai Duong - Nguyen Huong, Bao Long, Ba Tien, Gia Bao, and others. Green bean cakes have become a source of pride for the people of Hai Duong.