For the record: you basically take a stick blender, the container that came with it, crack an egg, pour over some lemon juice, then blend while pouring in hot butter (use the microwave!). Takes ca 2 minutes, including the 1 minute 30s of microwaving the butter.

Instant _real_ sauce hollandaise as the stick blender creates a vortex that emulsifies it. No need to hand whisk it over a bain-marie at careful temperatures.

Has anyone tried ultrasound (either probe or basin) for this mixing? I know it can be done for a finer substance