Gloucester Sauce

Sauce Gloucester (a cold mayonnaise sauce for meats) teaches the quiet discipline of loosening an emulsion without undoing it. The one true thing to know before touching a pan is that there is no pan: very thick mayonnaise receives lemoned sour cream by degrees. Pour the cream in at once and the sauce can turn loose and greasy; feed it slowly and it becomes pale, glossy, and properly spoonable.

The original entry begins with a pint of mayonnaise and assumes a saucier with that foundation already made, plus enough cold meat to justify the quantity. At home, use a bowl, a small whisk, and one cup of excellent thick mayonnaise. The batch is reduced, but the book's five parts mayonnaise to one part sour cream remains intact, with the lemon, fennel, and Worcester sauce scaled beside it. The service quantity is brigade scaffolding and can go. Gradual incorporation is the dish and must stay. A stockpot and salamander have no work here. One cook, one stove, one evening.

Finished Sauce Gloucester should lie in a soft fold from the spoon, rich but freshly acidulated, with fennel lifting the cream and Worcester sauce giving a discreet savoury edge. Whisk the sour cream and lemon perfectly smooth first, then add that mixture to the mayonnaise in small measures. That gradual addition is the step that matters most.