Shrimp Butter

A classic compound butter from Ranhofer's The Epicurean, built by pounding whole shrimp — shells and all — into butter and then forcing the mixture through a sieve. The sieving is not optional; it is the entire point of the technique.

• Use cooked shrimpThe recipe does not say, but shrimp would normally have reached a nineteenth-century kitchen already boiled. Use small cooked shell-on shrimp; raw shrimp will give a duller butter.
• The shells carry the flavorPounding "without removing their skins" is deliberate. Much of the aroma and most of the color sit in the shells, and the butter fat extracts both. Peeled shrimp make a paler, weaker version.
• Lobster coralCoral is the roe of a female lobster, dark green when raw and scarlet once cooked. It is a coloring and thickening agent here as much as a flavor. Two ounces is roughly the yield of one or two hen lobsters, and it is hard to buy on its own; if you cannot get it, the butter will simply be paler and less rich.
• Machinery instead of a mortarA food processor will do the pounding in a minute or two, but it does not replace the sieve. Work the pounded paste through a fine drum sieve or a chinois with a ladle; shell fragments left in the butter are unpleasant and will scratch. Expect to discard a fair volume of spent shell.
• Warm the butter, don't melt itSoftened butter at about 65F takes the pounding and passes through a sieve. Melted butter separates and the shell debris floats through with it.
• SeasoningNo quantities are given for the salt, cayenne or lemon. Start with about half a teaspoon of salt and a pinch of cayenne per pound of butter, taste, and add the juice of half a lemon at a time — acid brightens the shrimp but too much makes the butter grainy.
• Yield and keepingAbout a pound and a quarter of finished butter. Roll it in parchment, refrigerate up to a week, or freeze for several months in slices. It is meant for finishing fish sauces, spreading on canapés, and mounting into a bisque off the heat.