Brown sauce is a condiment that is normally dark brown in colour. Its taste is either tart or sweet with a peppery note similar to that of Worcestershire sauce. A.1. Sauce was the first brown sauce and was introduced in 1831. From Wikipedia
The banquet, marking the first state visit to China by Pakistan's Prime Minister, featured delicacies such as 'Consommé of Swallow Nest and White Agaric,' 'Shark’s Fin in Brown Sauce,' and 'Roast Peking Duck.'
