The fried dough side commonly dipped into pho today is quẩy. It is a deep-fried wheat-flour dough, usually made in elongated or joined pieces, and is served alongside the soup so diners can dip it into the savory broth.
The custom grew out of hardship during Vietnam’s subsidy period. When state-run eateries often lacked meat and rice, bread or cold rice could accompany a bowl of pho. That practice helped establish the modern habit of eating quẩy with pho, even after restaurants returned to more conventional ingredients.
Quẩy is closely related to youtiao, the Chinese fried dough stick known by related names across East and Southeast Asia. In Vietnam, the word can refer to the plain fried sticks served with soup; other forms include twisted sweet doughnuts. It is not the same as bánh bao, a steamed bun, chả giò, a fried spring roll, or bánh xèo, a savory rice-flour pancake.