Despite its name containing the Vietnamese word for 'beef,' the roll has never traditionally held any beef at all — it's a Vietnamese spin on popiah, a wrap the Hokkien call 'lun piah,' the same root that gave the Philippines and Indonesia the word 'lumpia.'
A thin rice-paper wrapper is rolled tightly around julienned jicama, carrot, Chinese sausage, egg strips, and dried shrimp, then sliced into bite-sized pieces and dipped in a sweet hoisin-peanut sauce. Street vendors around Saigon sell them cut and stacked on a plate, a cheap, room-temperature snack that needs no cooking on the spot.