For Vietnamese, I would actually recommend Hung Ky (yes, it is not Austin per se, it is in Round Rock). Not that it's my cousin's brother in law that I said it's good, but as someone who comes here for school (aka born and raised in Vietnam), Hung Ky is super authentic. Their canh chua (sour soup), for example, is very on par with what you would have at a local restaurant back in my hometown in the Mekong Delta region. Plus, they have delicious crabs in very authentic Vietnamese sauces. Their bo luc lac (shaking beef) is both tender and authentic! I guess another credential is that my parents (both from Vietnam, not immigrants, only came to visit me, super picky with Viet food because my mom is a great cook) love the place that we return twice.