Aurora Sauce
Aurora sauce for fish is prepared by adding to one pint of thick tomato sauce, one-half of a cupful of chopped canned mushrooms, two tablespoonfuls of mushroom liquor and one tablespoonful of butter cut into bits, and stirring until the butter is absorbed.
A short finishing sauce that depends almost entirely on how the butter goes in. Everything else is assembly.
- The hinge: butter off the heatThe hinge: how the butter goes in -- Cut the butter cold and add it in bits, ideally with the pan off the burner, stirring until it disappears into the sauce. Hard boiling after the butter is in can make it separate and sit as a film on top rather than blending in.
- "Thick tomato sauce"Best read as a tomato sauce already reduced to coating consistency rather than a thin sauce poured straight from the tin. If yours is thin, start with more than a pint and reduce it so that you still have a full pint of thick sauce; the mushroom liquor will loosen it again.
- Mushroom liquorThe liquid from the can. With fresh mushrooms there is none, so sauté 4 oz sliced mushrooms in a little butter, deglaze the pan with two tablespoons of water or dry white wine, and use that. Dried mushroom soaking liquid also works and is stronger.
- Canned mushroomsCanned mushrooms of this era were commonly whole buttons and were often on the salty side. Modern canned pieces will serve; drain them and taste the sauce for salt before adding any.
- Half a cupful, choppedRoughly 2 to 3 oz of drained mushrooms once chopped. Chop them fine enough that the sauce still pours.
- Yield and servingAbout a pint and a quarter, enough to nap six to eight fish portions. Spoon it over poached or baked white fish at the table; it does not hold well kept hot, and reheating it hard will split the butter.
The name is borrowed from French classical cookery, where sauce aurore is a white sauce — velouté or béchamel — tinted rose with tomato purée and finished with butter, its name generally traced to Aurora, the dawn, for that pink colour. This version inverts the proportions: tomato is the base and butter only the finish, which is a good deal less work than making a velouté first. It relies on canned mushrooms and their liquor, called for without comment, as for an ingredient a household cookbook could take for granted.