Shrimp Sauce

A shell-and-all shrimp essence thickened with a butter-flour paste — closer to a small bisque than a modern cream sauce. It works, but a few of the instructions assume knowledge the book did not bother to spell out.

• "Papa rika"A typesetter's mangling of paprika. Use sweet Hungarian paprika, about a quarter teaspoon; it is there for colour and warmth, not heat.
• Pounding shellsMuch of this sauce's flavour comes from the shells, which is why the recipe says "skins and all". A mortar is slow but effective; a food processor pulsed hard does the same job in seconds. Do not skip the pounding and simply simmer whole shells — the extraction will be thin.
• Butter and flour pasteThis is a beurre manié, worked cold, not a cooked roux. Pouring the hot liquor over it will not cook out the raw flour taste on its own; whisk the combined sauce over low heat for three or four minutes until it loses its floury smell and thickens.
• Strain twiceA "puree strainer" was a fine sieve worked with a wooden pestle or spoon. Press hard through a fine sieve, then pass the liquor through cheesecloth or a chinois — pounded shell leaves grit that a single straining will not catch.
• Season the anchovy firstA teaspoon of anchovy paste carries a good deal of salt, as do the shrimp themselves. Add it, taste, then add salt if it still needs it.
• The finishing shrimpThe recipe does not say whether the finishing shrimp are already cooked. If cooked, they need only to heat through — thirty seconds to a minute in the hot sauce, since held longer they turn rubbery; if raw, give them long enough to cook through. Either way, the instruction to serve it very hot means immediately, not held on the stove.
• Consistency and yieldA tablespoon each of butter and flour to roughly a cup of liquor gives a light-to-medium bodied sauce, and after boiling and straining you will have a scant cup — enough for two or three portions of fish. Loosen with a little fish stock or cream if it sets up too heavily on standing.