Divide butter into thirds and soak in ice-cold water. Beat egg yolks, cold water, and lemon juice in top of double boiler.
Place this over very hot (not simmering or boiling) water. Continue beating with a wire whisk and add 1/3 of the butter.
When it melts, add another third-but continue whisking. Then add the last third. When this has melted and blended well, remove from the hot water and add seasonings. Should the sauce seem too thick for your taste, thin it with a bit of hot water.