Caviar Hollandaise: Building and Finishing an Emulsion Sauce. Hollandaise is one of the French mother sauces and among the most temperamental — an emulsion of egg yolks and clarified butter that can split in seconds if rushed. The key is temperature: the yolks must be whisked over barely simmering water until they thicken to a ribbon stage before any butter is introduced, and the clarified butter must be added in a thread-thin stream while whisking constantly. If the sauce thickens too quickly, a teaspoon of warm water loosens it without breaking the emulsion. The balance of lemon juice and cayenne is critical — hollandaise must taste bright and lifted, not heavy, especially when served over rich duck-fat confit fish where it needs to cut through rather than compound the richness. When finishing with caviar, fold it in gently off the heat at the very last moment so the eggs remain intact and provide distinct pops of salinity rather than dissolving into the sauce. Monica Galetti described the hollandaise wrapping around the halibut like a blanket — this generosity of application is part of the dish's luxury.