Beef – use cow feet in pho broth

Full disclosure — I'm not Vietnamese :-)

The word "pho" (actually "Phở") is a corruption of the French word "feu", as in "Pot au Feu", the dish that it can claim as its ancestor. (That's from a Smithsonian Magazine article about Vietnamese food from sometime in the past few years.)

It's a stock-based brothy soup, usually with at least onions and rice noodles and often (by customer choice) one or more meat additions. Sometimes the meat is added raw to the boiling hot soup immediately before serving. The dish is almost always served with a side platter of fresh herbs, bean sprouts, sliced-up chiles, and lime. The herbs are usually something like mint, Thai basil, and cilantro (or equivalent).

It's not a super-fancy dish, and to my knowledge there's no International Phở Licensing Board, so the rules as to what is and isn't "correct" are probably pretty loose. I've had an awesome veggie-broth Phở, for example.

No, it's not unusual at all. See this page from Vietnamese-American cooks for examples where nuoc-mam is used to marinate chicken, or just type

nuoc mam marinade

in Google :)

There are a lot of examples, including fish, chicken, beef, or even mango marinated (as well as dipped, of course) with nuoc-mam (and most of the time lemongrass), and a fair share of them are recipes by 'natives' from South-East Asia, not only fusion food addicts (even if you can be both!). Some salads like goi tom or goi ga also involve nuoc mam marinade.