1tbls white wine vinegar
Pinch of salt
Melt the butter until it's liquid. Heat up a wok half way with water, yolk vinegar water and salt beat up in a metal bowl over the wok for double boil. Wait til it peaks but don't let it become scrambled egg. Food processor the yolk, vinegar, water and salt and slowly add the melted butter so it doesn't split.
I wasn't sure this was the correct way to make hollandaise, since my father adds tarragon to make bearnaise sauce.