Development
When did vendors begin experimenting with sesame oil and tofu?
Pho
In the late 1920s, various vendors experimented with (a seasoning made of ground cinnamon, star anise, , and clove), sesame oil, tofu, and even "Lethocerus indicus" extract (""). This "" failed to enter the mainstream. "", served with beef cooked rare, had been introduced by 1930. Chicken pho appeared in 1939, possibly because beef was not sold at the markets on Mondays and Fridays at the time. With the Partition of Vietnam in 1954, over a million people fled North Vietnam for the South. Pho, previously unpopular in the South, suddenly took off. No longer confined to northern culinary traditions, variations in meat and broth appeared, and additional garnishes, such as lime, bean sprouts, culantro ('), cinnamon basil ('), and Hoisin sauce ('), became standard fare. ' also began to rival fully cooked "" in popularity. Meanwhile, in North Vietnam, private pho restaurants were nationalized ("") and began serving pho noodles made from old rice, while street vendors were expected to use noodles made of imported potato flour. During the so-called "" after the War, state-owned pho eateries served a meatless variety of the dish known as "pilotless pho" ('), in reference to the U.S. military's . The broth consisted of boiled water with MSG added for taste, as there were often shortages on various foodstuffs like meat and rice during that period. Bread or cold rice was often served as a side dish, leading to the present-day practice of dipping ' in pho.