Emulsified Butter Sauces

In search of lightness, more and more chefs have turned to the delicate emulsified sauces whose principal ingredient is butter. Chief among these are two sauces based on egg yolks—hollandaise, flavored with lemon juice, and béarnaise, flavored with vinegar, shallot and tarragon. The third basic butter sauce, white butter sauce, is not stabilized by the addition of egg yolks. It is thinner and separates more easily than hollandaise or béarnaise. The quality of all three sauces depends on using the best fresh unsalted butter. For a smoother hollandaise, use clarified butter.