There was a thread on Chowhound about the use of fresh crab in bun rieu, and it seems like two places have(had) it: Rang Dong and (now closed) Bun Mam Soc Trang. I haven’t tried either but I have tried a lot of versions, including a good one in Hanoi.
In my opinion it is one of the most failed dishes in American Vietnamese restaurants, ie there are a lot of crap versions that veer far from the original dish. Even though I would love to try one of the fresh crab versions, my favorite thus far is at Tay Ho in Oakland. It is my favorite noodle soup there, and often trumps their fantastic crispy crepe if I only get to choose one dish for my meal.
