She may be edging into her nineties, but Tran Thi Tam still refuses to serve her children store-bought banh chung, the savoury rice cake prepared in a frenzy during Vietnam's lunar new year festival known as Tet.
Instead, the 89-year-old Hanoi resident and her children spend more than a day assembling the Vietnamese delicacy made of sticky rice, beans and pork wrapped in green leaves and tied with bamboo string.
"Banh chung made outside the house is never good," she insists.
The wrapped cakes, which must be boiled for 12 hours before they are ready to eat, are one of several dishes prepared specially for Tet, the week-long holiday in Vietnam that sees nearly all schools and offices close.
A woman sells traditional rice cakes called "banh chung" on a Hanoi street.
Families gather to ring in the new year -- which will start on 8 February -- and carry out a host of rituals, such as giving gifts and red envelops of cash, cleaning and decorating homes and firing up elaborate feasts.
According to an oft-told legend, the banh chung recipe was first prepared thousands of years ago by a Vietnamese prince who wanted to impress his father in a bid for the throne. Pleased with the cake's flavour and impressed with his son's demonstration of respect, the king duly handed down his crown.
Today the cakes are laid at family altars as an offering to ancestors, who are widely venerated in Vietnam -- a country that is officially atheist but still steeped in Confucian social mores.
A Vietnamese farmer waits for customers ahead of the Vietnamese "Tet" (Lunar New Year festival) in a peach blossom flowers field in Hanoi, Vietnam, February 2, 2016.
It's become increasingly common for families to buy the dish from specialty sellers instead of making them from scratch.
But rumours have bubbled in recent years about commercial banh chung makers who try to speed up the lengthy preparation by dropping a battery into the boiling pot of cakes -- a method that Vietnam's state-run television warned was dangerous and ineffective in a report this week.
The broadcaster urged viewers to call immediately if there is "clear evidence of any establishments using a battery to cook banh chung".
For Tam, this is just another reason to keep the cooking under her own roof.
"I will never buy the ready-made banh chung," she said.