A Gastrique is a subtle, syrupy, French sweet and sour sauce. It can be used on its own as a drizzle, particularly with meats such as pork, game, or strongly-flavoured fowl, or added to sauces, as it is in classic versions of Duck à l’orange.
A simple version is made by melting white sugar until it has carmelized to brown. This takes the blunt edge off the sweetness. Then wine vinegar is added, and the mixture is simmered briefly to make a thick syrup. The vinegar can be wine vinegar, raspberry vinegar, sherry vinegar, etc.
Prepared like this, you use it as a seasoning, so to speak, for a main sauce. You add it little by little to the main sauce until the taste is where you want it. (If you find your main sauce needs a bit more sour, then you can often balance it with a few drops of wine vinegar stirred right in.)
A simple gastrique such as this can also be used in fruit dishes.
Increasing, modern recipes for gastrique prepare it almost as one would a coulis, or drizzle. These typically use fruit juices in addition to or in place of the sugar.
In another meaning of the term, gastrique doesn’t have to have sugar in it (either actual sugar, or fruit.) It can be like the base of a Béarnaise sauce: vinegar, wine and shallots, with the sweetness coming from whatever sweetness is in the wine and the shallots.
Some versions use honey and sugar as the sweetener; some use another form of acid, such as orange juice. Some have you start first with vinegar, and then add another acid for more flavour.
A similar Italian preparation is called “agrodulce.”
Proportions of sugar to vinegar vary for a simple gastrique:
- 2 tablespoons sugar to 3 tablespoon wine vinegar
- 3 tablespoons sugar to 4 tablespoon vinegar
Etc. In general, the ratio is 2 part sugar, 1 part vinegar.
You first make a “dry caramel” (caramel à sec) by putting sugar in frying pan, and begin heating the sugar over medium heat. The sugar will start to melt, and then within very little time, the melted sugar will start to brown as it begins to caramelize.
When the sugar is all melted and nicely caramelized (it may even have hardened in a few places, not to worry) you add the vinegar to “deglaze the pan”. Beware of splattering when you add liquid to the hot caramel. Reduce the heat, and stir until the sugar dissolves into the vinegar. Let simmer to thicken a bit. Add more wine vinegar if need to make a syrup of desired thinness. Bear in mind that the gastrique will thicken as it cools. Remove from heat.
Simple gastriques will keep in the fridge for up to 6 months.
Fruit gastriques, store in fridge for up to 2 weeks, or freeze.
Gastrique in French means “related to the stomach.”