One piece of food I can not live without, is Tom Yam Goong, a hot and sour soup with shrimps, ginger and lemongrass as the main ingredients.
Tried it in many countries outside Thailand, but they make a total crap out of it. Even in Thai restaurants. Now that I'm in the country, I eat it every day with hopes that one day it'll be enough for me.
Unfortunately, no noticeable success so far.