Gastrique

Gastrique is a classical French sauce obtained by caramelising sugar with vinegar, generally used as a sweet-and-sour sauce base to accompany duck, pigeon and feathered game. The classical ratio is one hundred grams of sugar to one hundred millilitres of vinegar, reduced until a dark brown syrup is obtained. The gastrique is then moistened by stock or jus to complete the sauce. The technique remains a pillar of French bourgeois cuisine and still figures in three star preparations attached to tradition (Source: Auguste Escoffier, Le Guide culinaire, 1903).