Sauce Bercy
Velouté: Sauce Bercy, bercy sauce
Sauce bercy is a classic sauce of French cuisine. The main ingredients are fish stock, velouté sauce, white wine, shallots and butter. Auguste Escoffier wrote in Le guide culinaire that sauce bercy is made to be served alongside fish.
Source: Wikipedia
Recipes

Adam Gopnik's Entrecôte with Sauce Bercy Recipe on Food52
At Chez René in Paris, they served sauce Bercy on the side, and it was so heavy with shallots that, at first, I thought it was just shallots, with some kind of warm vinaigrette added. But it isn’t: It’s a proper, cooked sauce of shallots with white wine...