For almost 50 years, residents of a Saigon hamlet have prepared thousands of sticky rice cakes for the summer cleansing festival.

The Banh u (pyramid sticky rice cake) is one of the essential dishes for Tet Doan Ngo, a Vietnamese summer festival during which people are believed to cleanse the body and spirit. This year, Tet Doan Ngo falls on Friday.

The festival, celebrated on the fifth day of the fifth lunar month, is also referred to as the pest killing festival. This year, three days before the festival, Nguyen Van Tri’s family started to prepare thousands of pyramid-shaped sticky rice cakes to sell on this occasion. In a small alley off Pham The Hien street, his family got busy making and wrapping the cake in bamboo leaves.

"The vocation of making sticky rice cake in bamboo leaves was introduced to this hamlet in 1975," Tri said. "Back then, everyone in this long alley was involved, but now, only 20 households are doing it now.

Tri recalled the happy time when Tet Doan Ngo approached, and the entire hamlet got busy, soaking the rice, washing the wrapping leaves and boiling the cake.

Tri checking the plastic basins in which sticky rice has been soaked in water drained from ashes of fragrant plants. "The rice has to be soaked for 2 days before it absorbs the aroma of the ash water. Every household makes several hundred kilograms of sticky rice and mung bean," said Tri.

After soaking, the mung bean is cooked with sugar, and rolled into small balls to create the cake filling.

"In every cake, we add a piece of squash candy to give the dish a stronger flavor. Every household makes thousands of mung bean balls, so we have to do this for at least one day before wrapping the cake," said Yen, who owns a cake making workshop.

The bundles of bamboo leaves are bought from southern Tay Ninh Province and carefully washed. The bamboo leaves must be large in size; each leaf has to be fresh, green and intact without any tear. These leaves would help shape the cake into its proper pyramid as also the light fragrance from the leaves.

Women usually take charge of wrapping the cakes, while men boil them and deliver to customers. The wrapped cakes are hung on thin bamboo sticks to make it easier for the cook to tie 60 pieces into one bundle.

"Almost every household has to make thousands of cakes, so sometimes people have to hire more people to finish the job. For the whole year, we only have this occasion, Tet Doan Ngo; so no matter how many cakes we make, they can be sold," said Bay Xuan, a cake maker.

Each bundle of cakes is put into a large pot to be boiled. The water level must always be higher than the cakes. Each big pot contains up to 500 cakes.

It takes about four hours for the cake to be fully cooked. During the process, the cook must keep an eye on the pots to add more water or firewood as needed.

Ovens are lit across the alley and smoke from the boiling pots pervades the place several nights before the summer cleansing festival.

Each bundle of cake has a wholesale price of about VND300,000 ($12.87).

"A cake is considered delicious when its bamboo leaf cover retains its green color. The outer layer of the cake must be light yellow, the filling of mung bean soft and the cake is brown," said Nguyen Thi Hoa, 60, a cake maker.

Phuong Hong Duyen, a District 11 resident, drops by the alley to buy 300 cakes to sell. "I only sell it online and it is in high demand. No matter how many cakes I sell, they are sold out. This year I will buy more to sell," she said.

Tet Doan Ngo is a traditional celebration in several Asian countries. In Vietnam, people believe that on this day, eating sticky rice cake, sweet soup, sour fruit and sticky rice wine in early mornings will help kill insects and diseases inside the bodies.