Chicken with Sauce

This is a liaison — egg yolks used to thicken and enrich a hot broth without any flour — attached to a chicken prepared elsewhere in the book. Almost everything that can go wrong happens in the last thirty seconds.

• The hinge: temper, then hold below a simmerWhisk a ladleful of the hot gravy into the beaten yolks first, then return the mixture to the pan off the heat, stirring constantly. Held between about 160F and 180F the sauce thickens to a light coating consistency; a single boil will scramble it into curds that cannot be smoothed out.
• What the base recipe suppliesSippets are pieces of toast, so the cross-referenced dish is most likely a gently cooked bird served over toast rather than a roast; on that reading the "gravy of the chicken" is its strained cooking liquid. Check the base recipe before assuming. If you are working from a modern poached chicken, reduce a cup of the cooking liquid by a third and skim it well before thickening.
• "A spoonful of water"Unspecified; period usage covers anything from a teaspoon to a tablespoon. Its only job is to loosen the yolks so they whisk smoothly and take the hot liquid without seizing, so err small.
• Quantities and yieldTwo yolks will thicken roughly a cup to a cup and a quarter of broth — enough sauce for one or two servings, which is the scale invalid cookery works at. Doubling the broth without adding yolks gives a thin, cloudy result.
• Eggs for a sick personThe sauce never gets a hard cook, and the intended eater is by definition unwell. Pasteurized eggs are the sensible choice here, and the sauce should be made to order rather than held warm or reheated.
• Seasoning the original assumesPeriod invalid dishes were deliberately bland, but a little salt and a few drops of lemon juice stirred in at the end lift the sauce without making it rich. Add acid after the yolks have set, not before, or it will encourage curdling.