This is the most basic of the egg and oil emulsified sauces. The only flavoring is fresh lemon juice. This sauce must be kept warm, as excessive heat will cause it to break. Because this is kept warm, it is not safe to keep it for long periods of time and should never be reused from another meal period.
Hollandaise sauce is an emulsion of butter and lemon juice using egg yolks as the emulsifying agent, usually seasoned with salt and a little black pepper or cayenne pepper. It is a French sauce, named because it was believed to have been, or to have mimicked, a Dutch sauce. Hollandaise sauce is well known as a key ingredient in eggs Benedict.