Sometimes a sauce needs thickening at the last minute and there are several traditional methods that do not require great skill. A beurre manié, simply equal amounts of flour and butter kneaded to a paste, added just before the end of cooking, thickens and enriches. As the butter melts it distributes the flour throughout the liquid. Other thickeners are cornflour, arrowroot or potato starch. These thicken with very little cooking as they work more quickly than wheat flour. Egg yolks and cream are used to thicken and enrich velouté sauces.
To make a beurre manié, knead together about 20g (¾oz) each plain flour and butter with a fork. Bung 300ml (½pint) sauce to the boil, then flick in small knobs of beurre manié, stimng until the sauce thickens. Beurre manié can be stored in the refrigerator for several weeks and used as necessary.
To use cornflour, arrowroot or potato starch to thicken 300ml (½pint) sauce, bring the sauce to the boil. Mix 2 teaspoons thickener with 1½ tablespoons cold water or stock, then whisk into the hot sauce, whisking until lightly thickened.
To thicken and enrich300ml (½pint) hot velouté sauce, mix 1egg yolk and 1-2tablespoonsdouble cream in a cup, then stir in alittlehot sauce. Whisk this mixture into the sauce over a low heat, whisking constantly until thickened. Do not boil.