rofl pho is probably the most famous vietnamese dish- it typically includes noodles served in a soup boiled with Col. Nguyen's 11 secret herbs and spices and various meats- personally my favourite is "pho dac biet" which is the noodles with a combination of different meats, including tripe- i know some people are turned off the idea of eating cow's stomach and spinal cord but trust me it's aweeeeesome!
but then again i have a taste for the quirky, my other favourite soup based dish is the korean "soondaeguk" which is a beef based stew with pork intestine sausages with buckwheat noodle filling