I made beurre blanc last night for the first time. It’s as simple as I’d been told. Following Bittman, mince two tablespoons of shallots, mix with 1/3 cup of white wine vinegar and 1/3 cup of white wine, and reduce to two or three tablespoons. Reduce heat as low as it can go, and add a stick of very cold butter, a small bit at a time, whisking each bit until melted before adding the next.
If you have fish stock around, you might follow Larousse Gastronomique and replace the wine with that instead. Bittman’s is more appropriate for the typical home cook, though.
I used it to top a nice salmon fillet.