Gastrique — Caramelised Sugar and Vinegar Reduction

A gastrique is caramelised sugar deglazed with vinegar — the sweet-acid base that underpins some of the most important preparations in the French canon: canard à l'orange, magret aux cerises, and every fruit-and-meat combination where sweetness must be present but cloying must be avoided. The gastrique provides controlled sweetness (from the caramel) and structural acidity (from the vinegar) in a single, concentrated preparation. The method is precise. Place 100g of white sugar in a heavy-bottomed saucepan — stainless steel or copper, not dark-coloured pans where you cannot judge the caramel colour. Add 2 tablespoons of water to help the sugar dissolve evenly. Heat over medium flame without stirring — stirring introduces air bubbles and promotes crystallisation. Watch the sugar progress through its stages: dissolved and clear (100°C), light amber (155°C), medium amber (165°C), dark amber (175°C). For most gastriques, medium amber is the target: the sugar should be the colour of dark honey, smell of toffee, and just begin to release wisps of smoke. The critical moment: add 100ml of vinegar to the hot caramel. This will erupt violently — steam, spatter, the sugar may seize into a hard mass. This is expected. Continue heating and stirring; the seized sugar will re-dissolve within 2-3 minutes. The choice of vinegar defines the gastrique's character: sherry vinegar for duck, red wine vinegar for red meat, cider vinegar for pork, white wine vinegar for neutral applications. Reduce until syrupy — the gastrique should coat a spoon thinly and drip in slow, viscous drops. At this concentration (roughly 50ml remaining from 100ml vinegar + 100g sugar), the gastrique can be stored indefinitely in the refrigerator. It is a building block, not a finished sauce — add it to demi-glace for duck preparations, to pan juices for quick sauces, or to vinaigrettes for sweet-acid balance.