It's the most common sight in Bangkok- a city where more than 10,000 vendors sell their own variations of a regional cuisine known as Isaan food. But just a couple of generations ago, this didn't exist at all in the capital. So what is Isaan food? Where does it come from and what are the key flavors? And after a few decades stewing in Bangkok's melting pot, what does the future hold for this humble and incredible cuisine?