Horseradish Sauce

A simple roux-thickened sauce, closer to a German Sahnesoße mit Kren than to the whipped-cream horseradish of English carving tables. It comes together in about five minutes and wants attention at only one point.

• Do not let it boil once the horseradish is inHeat drives off the volatile isothiocyanates that give grated horseradish its bite, and prolonged cooking turns the flavour flat and cabbagey. Bring the thickened base to a boil first, then take it down to a bare steam before stirring the root in.
• Butter the size of an eggRoughly 2 ounces, about 4 tablespoons. With half a tablespoon of flour this is a very loose ratio, so expect a thin, pourable sauce rather than a coating one; add another half tablespoon of flour if you want it to cling.
• The liquidA cupful of warm meat broth gives the savoury version usually served with boiled beef. The printed alternative reads "hot mint," almost certainly a misprint for "hot milk," which would give the paler, milder version; whichever you use, add it warm to the butter-and-flour paste to avoid lumps.
• Grated horseradishTwo tablespoons of freshly grated root is a moderate amount for a cup of sauce. Bottled prepared horseradish is packed in vinegar and is often milder by volume, so you may want closer to three tablespoons; taste before adding the salt, since bottled preparations are frequently salted already.
• Grating the rootPeel and grate it at the last moment and keep your face away from the bowl; the pungency peaks within minutes of grating and fades quickly thereafter.
• Yield and servingAbout one cup, enough for four to six. It is a hot sauce, meant to go straight from pan to table over boiled beef, tongue, or poached fish.