Bernaise sauce is an emulsion of clarified butter and egg yolk with the distinct flavoring of tarragon, shallots, and chervil. Called Sauce Béarnaise in French for the region in which it originated, the name is accurately spelled Bearnaise; however, it is frequently spelled Bernaise, leading to the mistaken assumption that it was named for the city of Bern in Switzerland. This sauce is best served with meat, poultry, or vegetables. Though several variations of recipes exist, it is a difficult sauce to perfect because it requires special attention to avoid separation and curdling. When prepared properly, it is smooth and creamy.
Varying recipes are easily found in cookbooks and online recipe forums and food sites, but the consistent ingredients include egg, butter, white wine vinegar, tarragon, shallots, and chervil. Tarragon is an herb and shallots are a variety of onion. Several recipes call for chervil, also an herb, and the beginning steps of the recipe usually require adding the three seasonings to white wine vinegar and cooking it into a glaze base. Some variations call for champagne, and many recipes consistently include cayenne pepper as well.
Cuisine experts say that the careful monitoring of heat is the biggest difficulty in the preparation of Bernaise sauce, as too high heat will cause the egg yolk to curdle and too low heat will not properly thicken the sauce. Similarly, adding the butter too quickly can cause the emulsion to separate and ruin the sauce. For the bold chef, the rewards of perfecting this sauce are best served over filet mignon, London broil, or other red meat. It also goes well with other meats, and certain vegetables can be enhanced by its flavor. Unlike Hollandaise, which is best reserved for eggs Benedict, Bernaise isn’t a great choice for egg dishes.
For the less bold who find perfecting anything in the kitchen difficult, there are pre-prepared Bernaise sauce mixes sold in grocery stores. Usually, only butter and egg yolk are added, but the cooking directions must be followed to avoid the same curdling and separation pitfalls mentioned above. Cooks can try this sauce as a different flavoring for their next dinner party or special dinner at home with a meat and side of asparagus or roasted potatoes, especially seasoned with garlic.