Oysters in Brown Sauce

A brown-roux oyster ragout meant as a filling for pastry shells. The whole dish turns on two things: browning the butter and flour properly, and keeping the oysters out of the heat until the last moment.

• Do not overcook the oysters"Parboil" here means dropping the shucked oysters into their own heated liquor only until the edges ruffle, roughly one to two minutes. They then go back into the finished sauce off the heat or over very low heat; more than a minute or two of simmering in the sauce makes them shrink and turn rubbery.
• A pint of oystersThat is a liquid pint of shucked oysters with their liquor, about 2 cups, or roughly 16 to 24 medium oysters. Shucked oysters sold by the pint at a fish counter are the same measure.
• Oyster liquorA pint of oysters may not yield a full cup of strained liquor, though parboiling releases more. Make up any shortfall with fish stock, bottled clam juice, or more milk rather than water, which dilutes the flavour. Strain through a fine sieve or cloth to catch grit and shell.
• Browning the rouxMelt the butter and let it go nut-brown before adding the flour, then keep stirring over moderate heat until the roux is the colour of milk chocolate, five to ten minutes. It will thicken less than a pale roux, so the sauce stays on the loose side, which is what you want in a patty case.
• Anchovy sauceThe commercial bottled anchovy sauce of the period was a thin salted essence. Anchovy paste is the nearest thing on a modern shelf; use about half a teaspoon, or a mashed anchovy fillet. Add it before the salt and taste, as both it and the oyster liquor are already salty.
• Vol-au-vents and patty casesFrozen puff pastry shells, baked and cooled, do the job. Fill them at the moment of serving; the sauce softens pastry within minutes.
• YieldEnough for six to eight small patty cases, or four servings over toast if you have no pastry.