Ok so....I did write and publish a big old post on this dish just a few days ago, but blogspot seems to have bloody lost it! Either that or I'm going mad.
Anyway here's a short version of what was previously here:
The pics are of 'cha ca thang long' in Hanoi, 'cha ca' for short - it's a delicious combination of turmeric marinated white fish (often 'snakehead' fish, or 'pla chorn' as it's known in Thai) along with fresh dill, chillies, peanuts, more herbs and some dipping sauce.
The dish is famous in Hanoi and there's loads of places to try it. I tried a few places, the best version I ate was here ...where the pics above are from.
Or make it at home, it's pretty straightforward, here's a good couple of recipes you might want to check out:
Great vid from Luke Nguyen: http://www.sbs.com.au/shows/lukenguyen/recipes/detail/recipe/11022
Nice version by the lovely people behind 'Ravenous Couple' (great sounding dipping sauce recipe there too): http://www.theravenouscouple.com/2009/06/cha-ca-thang-long-vietnamese-turmeric-fish-with-dill.html