A Saigon street-food recipe that traveled through three generations

The recipe exists nowhere in writing. It lives in the hands of 71-year-old Bà Sáu, who learned it from her mother on a curbside stall in Saigon, and who has spent the last four decades adjusting it, ingredient by ingredient, to whatever a given city's grocery stores could actually provide.

Bún riêu — a tomato-based crab and pork broth served over rice vermicelli — depends heavily on freshwater field crab, pounded into a paste that forms the distinctive floating "cake" on top of the bowl. That crab is nearly impossible to find outside Vietnam, which forced the recipe's first major adaptation: a substitution of canned crab meat blended with ground pork, a compromise Bà Sáu still apologizes for unprompted.

"My mother would be so upset," she said, laughing, while pounding the substitute paste in a stone mortar anyway, out of habit more than necessity at this point. "But what am I supposed to do, fly crab in from the Mekong Delta every week?"

Her daughter, who now helps run the family's small weekend pop-up out of a rented commercial kitchen, has made her own adjustments in turn — dialing back the fermented shrimp paste that used to anchor the broth's funk, after one too many customers asked what the smell was. Her own daughter, in turn, has started experimenting with a version that skips pork entirely for a college roommate who doesn't eat meat.

Three generations in, the bowl looks recognizably like the one served on that Saigon curb decades ago — and also nothing like it at all, depending on which ingredient you're asking about. Bà Sáu has made peace with that. "A recipe that never changes is a recipe nobody's cooking anymore," she said. "This one's still alive."