2 hours ago, Anna N said:Over in the breakfast thread we seemed to get very much off topic discussing how to make hollandaise. This seems a much better place to discuss that. @rotuts suggested that I try to recover a broken holidays by adding another egg yolk. I knew that was one option but I was not sure it was going to work being inexperienced in this technique. So I opted for the tablespoon of water as a cheaper option. It worked very well. Perhaps the next time I would use a yolk.
The classic repair method is to beat an egg yolk with about 15ml cool water or heavy cream. Then whisk the broken sauce into this emulsion, very slowly at first. Once you have a decent quantity of repaired sauce, you can go much faster. You'll lose a bit of lightness because you're deflating the sabayon, but the result should as smooth and stable as new.
If your holding temperature goes above 158°F, the sauce will probably break. It can also break from losing too much water to evaporation, so it should be kept covered.