Melt butter on low heat and set aside.
Whisk egg yolks in the top part of a double boiler.
Set pan over hot, not boiling, water and whisk until yolks are thick, sticky and creamy.
Add water and lemon juice and beat 30 seconds.
Drop in 1 tablespoon cold butter and beat 1 minute until mixture thickens, smoothly.
Remove from over heat and beat in another tablespoon cold butter.
Beat in the melted butter, 1/4 teaspoon at a time, until sauce thickens to a sour cream consistency; then pour butter in more rapidly, beating after each addition.
Discard the milky sediment in the butter pan.
Season to taste and keep warm by setting the pan in a bowl of warm, not hot water.(Hollandaise should be served warm, not hot.)
If too thick, beat in 1 or 2 tablespoons hot water, milk or cream.