Old Sour sauce

Old sour is a sauce used in the Bahamas and Key West, Florida. Old sour sauce originated in the Bahamas, and was originally prepared using key lime juice, salt and bird peppers. It is made from an aged mixture of lime (fruit) juice and salt. Old Sour has a salty and acidic flavor. Hot sauce is sometimes used to add additional flavor. Conchs, natives of Key West, use the sauce for a variety of food including seafood dishes. The sauce may have been developed to preserve lime juice.

Source: Wikipedia