Vu Bang looked forward to the rare autumn days when light rain and sunshine mingled in the clouds.
In addition to rainbows, Bang looked to sun showers as a sign of the fish bait feasts to come.
On those rare and beautiful days, farmers in the Red River Delta dropped whatever they were doing to skim ragworms out of the brackish waters north of the capital, throw them on ice and make a beeline for the city center.
His book, Hanoi Delicacies, contains a lengthy description of the days when cooks patiently awaited these harried farmers as they rushed through alleys in fear of the moment when their buckets of prized worms might turn from a lively red to a toxic, smelly green. Wise housewives, Bang noted, had to work just as fast.
A northerner at heart, Vu Bang even remarked: “An autumn without ragworms feels as tragic as a woman who has wasted her youth.”
Ragworms, unlike laggard ladies, never waste a single second. During high tides, the species engages in a passionate mating ritual that ends in the death of the male and (if Bang has his druthers) the netting of the female.
Despite the capital's rapacious appetite, thousands of fertilized eggs manage to find their way to the roots of riparian rice stalks.
In addition to the creature's amazing timing, Bang prized them for their crunchy, nourishing meat.
The poshest Hanoi households fried the prized worms in omelets scented with tangerine peel, creating an invigorating delicacy typically reserved for old folk suffering from creaky bones.
As a spy stuck in Saigon during the sixties, Vu Bang pined for the rare arrival of a package of fried or fermented ragworms.
During the 19th century, Hanoi's booming ragworm business leant its name to one of the 36 streets in its Old Quarter.
Though Ragworm Street now blooms with fake flowers, a sizzling omelet can still be found at many family stalls around the city's buzzing core.
Fresh out of the bucket
In the two-meter Hang Chai alley, a short walk from Ragworm Street, Quan spreads out a floral tablecloth before laying out pots of spices and a slender bench.
A favorite of local food writers, Quan proudly told VnExpress International how the tasty worms had provided him a small fortune and put his children through school.
Live ragworms fetch around VND500,000/kg ($23/kg) in addition to a long-distance delivery fee. Quan sells a few kilograms per day to his regulars.
The greasy heft of Quan's ragworm omelet is mitigated, somewhat, by a few dunks in watery fish sauce and the addition of fermented papaya, cilantro and packed rice noodles.
While home cooks might freeze live ragworms to keep them through the season, Quan disdains the practice. When the worms retire for the season he returns to selling noodles and waits patiently until autumn to pick up his spatula.
Why frozen ragworms?
Vu Bang himself approved of just two methods for preparing: a fresh catch-frying or fermentation.
What might he make of the vacuum-sealed bags now used to stave off spoiling for months?
One 19-year-old ragworm stall at the end of Lo Duc Street serves the critters every month of the year, except July.
Hang, a chubby old hand, claimed there were now two ragworm seasons: spring and fall. "During the rest of the year, we sell less, and meet our needs with pork meatballs, bun cha, spring rolls…”.
Since 1997, Hang has relied on a freezer to help her meet demand, which can stretch up to a few dozen kilograms per day. She also ships vacuum-sealed bags to customers pining away for them in central and southern Vietnam.
In some ways, it seems, Hang provides a humble year-round stop-gap for ragworm junkies like Vu Bang.
Duc, a middle-aged regular of Hang's, admitted he could taste the freezer.
“In my hometown, my wife picks out live ragworms at the market and fries them up with eggs," he said, munching away. "Hers are way better but I can live with these. Good enough.”