No. 441

Caper Sauce

Sauce aux Capres

Set into a saucepan two ounces of butter, mix it with one and a half ounces of flour; beat the flour and butter well together with a spoon, so as to obtain a smooth paste; now moisten it with two gills of water, add a pinch of salt, stir the liquid on the fire until the sauce becomes thick. At the first boil, remove it to the side of the range. It should be somewhat more consistent than thin. Incorporate into it gradually, two ounces of butter divided into small pats, the sauce should now be creamy; remove it and finish by adding some small nonpareil capers, and the juice of a lemon; then serve.

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For the Modern Kitchen

A plain white roux sauce finished with cold butter — essentially a butter sauce with capers, and the finishing is where it succeeds or fails. Ranhofer gives no yield; this makes about 1 1/4 cups, enough for four servings of boiled fish or mutton.

The hinge: butter off the heatThe second two ounces of butter must go in pat by pat with the pan off direct heat, each one whisked in before the next. If the sauce returns to a boil the butter breaks out as grease and the creamy texture is gone.
Two gillsA gill is half a cup, so two gills is one cup of water. With two ounces of butter and an ounce and a half of flour that is a fairly tight roux, which is what Ranhofer wants — he asks for something "more consistent than thin" before any finishing butter goes in.
Water, not stockThe base here is water rather than stock, which keeps the sauce neutral and lean; a fish fumet or light chicken stock gives a rounder result where leanness is not wanted.
NonpareilsNonpareil capers are the smallest grade, roughly 7mm, and still sold under that name. Brined ones should be drained; salt-packed ones need rinsing and a soak, or the sauce turns aggressively salty.
Salt at the start onlyThe pinch of salt goes into the roux, before capers and lemon. Taste again at the very end rather than seasoning ahead — the capers bring a good deal of salt with them.
A whole lemon is a lotThe juice of one lemon in a cup of sauce is sharp by modern palates. Add it in stages and stop where the sauce brightens rather than puckers.
Cook the flourRanhofer says only to beat the butter and flour to a smooth paste before moistening. A couple of minutes of stirring over low heat first will take off the raw-flour taste; keep the heat low so the roux takes no colour.
Holding itThe sauce will not sit over heat once the finishing butter is in. Keep it in a warm bain-marie below 160F and whisk before serving; do not reheat it directly.

A Little History

Charles Ranhofer's The Epicurean (1894) set down the kitchen of Delmonico's in New York, where he was chef for over thirty years, and its sauce chapters follow the French classical system he had trained in. Caper sauce belongs to a family of white sauces built on a roux and finished with cold butter. Capers themselves are the unopened flower buds of Capparis spinosa, pickled since antiquity around the Mediterranean and long imported into northern kitchens as a shelf-stable source of sharpness; the pairing of caper sauce with boiled mutton is an English habit that predates Ranhofer by well over a century. The word nonpareil, "without equal," is simply the trade term for the smallest and most prized grade of bud.