Beurre Blanc

Boil down 100 ml dry white wine, 50 ml white wine vinegar and a minced shallot in a small pan until about two tablespoons of syrupy liquid are left. Turn the heat to low and whisk in 200 g of cold butter, cut into cubes, a few at a time. Each batch should melt to a creamy texture before you add the next. The sauce must stay warm, not hot; if it gets too hot, the butter separates into oil. Season and strain if you like. Serve it with white fish, scallops and asparagus.