Long confined to Vietnam and immigrant communities, pho is becoming the most popular Asian noodle soup in the United States. Check the phone book for pho in Santa Clara and San Jose and you'll find more than 25 listings, including mom-and-pop operations and the prolific Pho Hoa franchises. One Southern California chain, Pho 2000, caters specifically to beef-loving Korean-Americans.
Pho has changed much during its nearly 100-year history. At its birth, pho was basically just boiled beef, noodles and broth. Inventive cooks then developed the raw beef version (pho bo tai) and chicken pho (pho ga), and during wartime when beef was scarce, they made pork pho (pho lon). Though these and other variations exist, most people define pho as a beefy affair.