I’ve been making this recipe for Hollandaise for mumble, mumble years.
One sauce pan over med high heat.
Constantly whisk 3 egg yolks and 2 T water.
Add a stick of unsalted butter one T at a time and constantly whisk until each is melted.
Whisk in 1 T lemon juice and a pinch of cayenne.
I’ve only had it curdle twice. If it does, it means you didn’t whisk it. Throw in some herbs, call it béarnaise sauce and no one is the wiser.
Use a spiral whisk so it gets to all the bottom of the pan.
IMO, it is vital to use clarified butter.
Also, if the water and vinegar you add is piping hot, it is easier to whip a lot of air into your sauce.