It's not even a big news to make a fortune by selling street food in Asia. Personally I know a family selling Pan-fried Stuffed Buns as street vendors in Taipei about 25 years ago. After 5 years or so they earned their buildings and moved in to a brick and mortar place in a neighborhood that's equivalent to the UES in NYC. Their business is still standing today, with three or more items on their menu. I would say they pretty much embed the "lean startup" spirit by surrounding their MVP, Pan-fried Stuffed Buns, from the beginning.