In Vietnamese tradition, the festival, held on the fifth day of the fifth lunar month, is associated with seasonal changes and customs believed to promote health and ward off illness.
Traditionally, people believed that eating fermented glutinous rice on an empty stomach during the festival could help ward off illness and kill pests in the body.
Fermented rice wine, known locally as ruou nep, is a staple of the occasion and is traditionally eaten in the morning. At Phu Thuong Ward, trays of freshly steamed glutinous rice filled courtyards as households rushed to prepare orders for the festival.
Ta Thi Hau, who has spent more than 16 years making sticky rice and rice wine, said the days leading up to Doan Ngo are the busiest of the year.
A batch typically begins in the morning and requires several hours of preparation before yeast is mixed into the cooled rice. The mixture is then fermented for two days before being packaged for sale.
Producers say the process requires careful temperature control and precise amounts of yeast to achieve the desired flavour and aroma.
"If too much yeast is added, the wine becomes bitter. Hot, dry weather can also affect fermentation and spoil a batch," Hau said.
She expects to produce more than 200 kilogrammes of rice wine this year, slightly less than in previous years due to production challenges.
After soaking, the glutinous rice is steamed twice, with careful draining between stages to achieve the desired texture.
Once cooked, the sticky rice is spread out to cool naturally before yeast is added in carefully measured amounts.
The rice is then fermented for two days, developing the sweetness and aroma that characterise Phu Thuong rice wine.
Accordign to Hau, if the rice is cooled too quickly or the yeast is added in the wrong proportion, the quality suffers. Hot, dry weather can also affect the fermentation process and spoil an entire batch.
Hau's family typically produced about 300 kilogrammes of rice wine for Tet Doan Ngo, but output has fallen to just over 200 kilogrammes this year due to more challenging production conditions.
"Prices are up by about VND 5,000 per kilogramme this year due to higher input costs. Purple glutinous rice wine now sells for around VND 70,000 per kilogramme, while white glutinous rice wine costs about VND 60,000," Hau said.
Le Thi Uyen's family in Phu Thuong has been working since the early hours of the morning to meet wholesale orders from Hanoi and neighbouring provinces.
Uyen said her household used nearly 700 kilogrammes of glutinous rice during the festival peak period and expects to produce more than one tonne of finished rice wine, almost double last year's output.
"We had to start steaming rice at 1.30 am to keep up with orders," she added.