Sauce Vin Blanc (White Wine Sauce)
The science
White wine contributes acidity and aromatic complexity; its alcohol must be cooked off so only flavor and acid remain. The acidity balances the richness of the butter mounted in at the end, and (in the liaison versions) helps stabilize the egg. Built on fish fumet — a quick, gelatin-rich stock of fish bones, aromatics, and often wine, simmered briefly to avoid bitterness — the sauce tastes specifically of the sea, which is the entire point of the fish-velouté branch.
Flavor profile
Fish velouté built around white wine, with shallot and a butter finish — the archetypal classical sauce for fish service. Several classical formulas exist: one reduces white wine and fish fumet, binds with a yolk liaison and mounts with butter; another simply finishes fish velouté with white wine and butter.
Culinary uses
Poached or à la nage sole, turbot, and other fine white fish; the canonical "fish in white wine sauce" of the classical repertoire.
Reference notes
Parent: fish Velouté. Technique: fish fumet; monter au beurre. Siblings: Bercy, Normande. Dishes: sole bonne femme, filets de sole.