Have a look at the little 'Unai's first day - behind the scenes' video.

[Sir C]

I've been doing it in a blender like that for some time with considerable success, so that makes sense. However, the problem with the blender is the bloody mess. this sounds better.

Exactly. I've used a blender but it seems like a big job.

Just think. Every time you cook a steak, a bearnaise is merely seconds away.