Thanks again Kuan. I appreciate the videos. I've never attempted a hollandaise sauce, but I'm still trying to understand how you scramble and egg, cook it, and don't end up with scrambled eggs. How do you know when you have enough butter in the mixture (volume or by "eye")?
Okay, some basics here.
1/2 eggshell cold water per egg yolk. 3 yolks is easiest in a standard pan, until you get the hang of it.
Whisk the c**p out of the yolk and water for 20-30 seconds, then put the pan over medium heat. Whisk steadily until it starts to thicken a bit. Whisk faster, and watch: suddenly the mix will turn nearly white and gain dramatically in volume, and you'll see the pan bottom as you whisk -- it's thick enough that you're pushing it out of the way instead of just stirring. Now whisk very fast for 20 seconds to finish cooking the yolks, remove from heat and whisk very fast 20-30 seconds to cool the mix enough that it won't keep cooking. You now have a sabayon.
Add seasonings: lemon for hollandaise, for example, but you want some acid, which will also help keep it from breaking. A little mustard is nice in more intense, savory sauces.
Now build the emulsion. Whisk steadily but not too fast, and add the fat (e.g. clarified butter) fairly slowly. Once it starts to thicken up and bind, you can add the fat more quickly. Don't whisk too fast, or you'll deflate the sauce, but don't add the fat too fast compared to the whisking or it'll break.
Use the fat by eye: when it's thick enough for your purposes, stop adding fat.
If your mise en place is good, you can do a hollandaise in under 2 minutes flat.
Warning: if you use few yolks, it thickens very, very fast, and can easily curdle (scrambled eggs). If you use a whole lot, it thickens slowly and can break remarkably fast if you don't know what to watch for. Start with 2-4 egg yolks and an appropriate-sized pan, and do it several times until you get the hang of it.
If you understand what you're doing, and know what you're looking for in the pan, you should be able to do it consistently with very few misses, even under pressure.