Gastrique is caramelized sugar
, deglazed with vinegar
, used as a flavoring for sauces.
To this a little fond (stock) may be added. It is used to flavor sauces such as tomato sauce
, savory fruit sauces, and other sweet and sour sauces such as the classic orange sauce for duck à l'orange.
Nowadays the term is frequently used to refer to any thus-flavored sauce itself, e.g. citrus gastrique, mango gastrique.
An agrodolce (sweet and sour) is a similar sauce found in Italian cuisine.