Soya Sauce

A classic French compound sauce that borrows a single Asian ingredient for depth and colour. Everything depends on the base sauce and on restraint with the salt.

• Two gills is one cupA gill is half a cup, so two gills of essence equals 8 fl oz. With a pint of velouté or espagnole you begin with three cups of liquid and reduce from there.
• What "essence" means hereNot an extract from a bottle but a strong stock of chicken, game or fish reduced until it is intensely flavoured and slightly syrupy. A well-reduced homemade stock, or a good demi-glace thinned to pouring consistency, stands in.
• Velouté and espagnoleVelouté is white stock thickened with a blond roux; espagnole is brown stock with a brown roux and a tomato-and-mirepoix base. Match the base to the dish: velouté with poultry or fish, espagnole with game and red meats.
• Salt disciplineEspagnole, reduced essence and soy sauce are each salty, and reduction concentrates all three. Season nothing until the butter is in and the sauce is finished.
• Reduce to about halfWhat "sufficient consistency" means -- the sauce should coat a spoon and leave a clear track when you draw a finger through it. The recipe gives no target volume or number of servings.
• The soy goes in off the heatWhen the soy goes in -- soy is commonly said to turn harsh and flatly salty if boiled hard, so it is worth adding once the reduction is done. The recipe itself says only to add it when the sauce has reached consistency; it does not direct you to pull the pan from the flame.
• Mounting with butter"beat in slowly with a whip" is the technique known as monter au beurre: butter whisked in a little at a time for gloss and body. Hold the finished sauce warm rather than returning it to a boil, or the butter may separate out.
• The soy of 1894Soya imported into nineteenth-century Europe and America was generally a dark, brewed, well-aged sauce. A naturally brewed dark soy, or a Japanese koikuchi, is likely closer to it than a light or low-sodium modern bottling.