Andrea Nguyen of Viet World Kitchen is a great writer as well as cook, and she has the curiosity to dig deep into the traditions and byways of Vietnamese cuisine. I don’t agree her on everything–her do chua is too sweet, and a bahn mi roll definitely needs rice flour in it–but this is a great starting point for your own Viet food explorations.
The blog is getting a little promotional these days with cookbook giveaways and what-not, so I recommend you bookmark the recipe index. Actually, start with this article–a great recipe and a history lesson rolled into one.