For one of the world’s most expensive delicacies, we journey to sourthern Thailand. Edible bird’s nest is made by a species of cave-dwelling swiftlets. Weaved from their saliva and harvested in caves and man-made nesting houses, bird’s nests are then painstakingly cleaned before being prepared as tonics. At over US$5000 per kilogram, bird’s nest is considered an elixir of youth.