Lemon Butter

A compound butter in its simplest form: fat, acid, nothing else. It belongs on hot broiled fish or a grilled steak, where it melts into a instant sauce.

• Quantities1/4 cup butter is 4 tablespoons, or half a standard American stick (about 2 oz / 57 g). One tablespoon of lemon juice is roughly the yield of half a small lemon.
• Butter temperature is the hingeThe butter must be soft enough to cream but still cool, not melted. Melted butter will not hold the juice and tends to separate into a greasy puddle with a sour layer beneath.
• Add the acid drop by drop"Slowly" is doing real work here. Beating the juice in a little at a time lets the water disperse through the fat as a stable emulsion; dumping it in at once will break the mixture.
• SeasoningThe original probably assumes salted butter, which was commonly available. With unsalted butter, work in about 1/4 teaspoon fine salt, and a pinch of white pepper if the butter is for fish.
• Shaping and storageRoll the finished butter in parchment into a log, chill until firm, and cut coins to lay on hot food. It keeps a week refrigerated and several months frozen.
• YieldAbout 5 tablespoons of finished butter; at a rounded teaspoon per serving that covers eight or more portions of fish or steak.