About the Recipe
White butter sauce
Though beurre nantais, also known as beurre blanc (meaning "white butter"), is not one of the five French mother sauces (béchamel, espagnole, hollandaise, tomato, and velouté), it is a base recipe from which many other sauces are built. This French butter sauce in particular does not have an emulsifier and relies solely on the butter, though cream may be used to help stabilize it or at least start the emulsion.
3 sticks cold unsalted butter (24 tablespoons), cut into tablespoon-sized chunks
1/4 cup dry white wine
1/4 cup white wine vinegar
1 tablespoon minced shallots
1/4 teaspoon kosher salt
1 pinch white pepper
1/2 teaspoon fresh lemon juice
Have the butter ready (cut and in a small bowl).
In a medium saucepan, bring wine and vinegar to a boil. Add shallots, salt, and pepper. Lower heat to a simmer and cook until most of the liquid has evaporated. (There should be about 1 1/2 tablespoons of liquid left. If you reduced it too far, add 1 tablespoon of water to remoisten.)
Remove pan from heat. Whisk 2 pieces of butter into the reduction.
Set pan over low heat and continue whisking butter into sauce a chunk at a time, allowing each piece to melt before adding more. Remember to maintain low heat and never let the sauce come to a boil once the butter is added, or the sauce will separate.
Remove sauce from heat and whisk in the lemon juice. Taste and adjust seasoning, then strain through a fine sieve into a bowl.