Leather Lane weekday market has been in this back street between Clerkenwell and Holborn for about 300 years. It's now a street full of pop-up food stalls from around the world. My personal favourite is Daddy Donkey's burritos and a coffee from the Prufrock. It's only open on weekdays 10-2pm and expect long queues for food!
Leather Ln, London EC1N 7TJ, UK