My cousin Tam gave me these directions. I believe they come from the Joy of Cooking. This is wonderfully easy and of course delicious, since it is nearly all butter.
1 stick of butter, melted. Keep hot
But in a blender:
3 large egg yolks
2 Tbsp. tarragon vinegar, or in my case 2 T sherry vinegar and about 1/2 teaspoon or more of dried tarragon
pinch of cayenne, optional
With the blender on, add the butter in a very slow stream.
If the sauce is not thick enough for your liking, put it back in the pot and heat over low heat, whisking until thick. Be careful not to break the sauce or cook the yolks. Tam says that if you break the sauce add an additional yolk to bring it back together.
For hollandaise sauce, use 2 Tbsp. of lemon juice instead of the vinegar.