One of Vietnam's national dishes is ph#7903;
(pronounced f#612;). It is a hearty soup.
Pho24 (named for the 24 "secret" ingredients in the soup) is the most popular food chain in Vietnam. There are outlets in major cities in Vietnam. They may also be found in Manila, Jakarta, Singapore, Seoul, and Sydney.
Here are some weblinks:
http://www.pho24.co.kr/ (this site is in Korean)
There are two popular Vietnamese fast foods. The other, besides ph#7903;, is bánh mì
(pronounced #712;b#652;n mi), which is a submarine sandwich, using the fantastic French baguettes you can get here.
There is a Vietnamese sandwich chain, based in Little Saigon (Orange County), California, called Lee's Sandwiches (the family name is actually "Le," but it was changed for esthetic purposes). Lee's Sandwiches doesn't sell ph#7903; and Pho24 doesn't sell bánh mì.
I think it would be great if these two chains could get together. I do like to eat my ph#7903; and bánh mì together!