Parsley Sauce
Make a white sauce and add chopped parsley and a little lemon juice. Serve with fish.
A one-line instruction that assumes the cook already knows the white sauce by heart. The proportions below are the standard ones a book of this period would have given a few pages earlier.
- The white sauce assumed hereEqual volumes of butter and flour — about 2 tablespoons each — cooked together without colouring, then whisked into 1 cup of hot milk. That makes roughly a cup of medium sauce, enough for four portions of fish.
- Cook the flour firstThe hinge of the whole thing. Let the butter and flour bubble together for two or three minutes before the milk goes in, or the sauce tastes of raw paste no matter how long it simmers afterwards.
- Parsley goes in lastChopped parsley added off the heat, or in the final minute, keeps its colour and its grassy edge. Simmered into the sauce it turns olive and tastes of hay. Flat-leaf or curly both work; curly was the more usual garden parsley in Anglo-American kitchens.
- Lemon juice at the endAcid added to a hot milk sauce can make it grainy if the sauce is at a hard boil. Take the pan off the heat, then stir in a teaspoon or two to taste.
- Season itThe original mentions no salt or pepper. Salt and white pepper are the usual finish, and some cooks add a scrape of nutmeg; white pepper keeps the sauce from being flecked.
- Fish liquor improves itIf the fish is poached, replace a third of the milk with the strained poaching liquid; it turns a plain sauce into something that belongs with the dish.
- YieldAbout one cup, serving four. Doubling is straightforward; keep the butter and flour equal.
Parsley sauce is the plainest branch of the family of English milk-and-flour sauces related to the French velouté and béchamel tradition, naturalised in British and American kitchens as "white sauce." Its pairing with boiled or poached fish was conventional enough that a cookbook could dispose of it in a single sentence and expect to be understood — the same base, with capers instead of parsley, went to boiled mutton, and with egg to salt cod.