Some wine - a cup, a shallot really finely minced up a bit of salt and pepper to taste and a whole lot of butter and bingo you have the sauce of the gods. Beurre Blanc is white butter...loosely translated. Bring the wine to heat and reduce and put the shallot in there to give added flavor (us peasants just drop a green onion piece in it for a bit to flavor the wine)....when the wine reduces by about 1/2 so the flavor concentrates (you can use vinegar (mild) if you want to give it a bit of bite), just start adding chunks of the butter and whisking it in. Eventually it will thicken up a bit but it shouldn't break down and get icky...just this light buttery sauce with a mild shallot onion flavor - salt and pepper to taste.
Over fish. Over lobster. Over asparagras...you name it. it takes just a few minutes and is a work of art. It is nice and tastes wonderful. It is bad for you so invite a dozen friends so they only get a tablespoon of butter each....but you all need to treat your tastebuds now and then. You just have to. It is a Julie and Julia YUM.