My best food tip? Ask your taxi driver for the best place to eat. You'll be pleasantly surprised. That's how I came to Lac Thien, a street cafe, for Banh Khoai--a savory crepe pan-fried to a golden crisp, stuffed with shrimp, bean sprouts and little mounds of pork. (Oh, trust me, you can't have just one.)
To eat, break a piece with chopsticks, add fresh herbs or wrap in lettuce, and dip in "tuong," a spicy garlic sauce.
Lac Thien is a tiny corner cafe at 6 Dinh Hoang, just off the Hue Trang Tien Bridge--perfect for people-watching.
P.S. Banh Khoai is a signature dish of the central region. In the States, you can find Banh Xeo (a larger variation) at most Vietnamese restaurants.