How To Totally Revive Broken Egg-Based Sauces
If you're making sauces at home, you're already in a league of your own. Maybe you even vaguely know the five "mother" sauces in French cooking (béchamel, velouté, espagnole, hollandaise, and tomato) which can be added to most meat, pasta, and vegetable dishes.
From this list, hollandaise is an egg-based sauce made from butter, lemon juice, and raw egg yolks. It stands out because it relies on the emulsification of eggs to get a creamy texture and tangy flavor. In theory, this is simple enough since it is a matter of whisking everything together. But the sauce tends to split, break or simply resist combining, just like water and oil.
The good news here is that it is possible to revive egg-based sauces, be it mayonnaise, aioli, hollandaise, or béarnaise sauce. What you need to do is make a fresh emulsifier and use it as a way to bind the broken sauce back together.
Keep some extra eggs for plan B
In a sauce like béchamel, which uses flour, butter, and milk, all the ingredients can easily mix together using heat. With an egg-based sauce, the heat alone is not enough because the melted butter (oil) and vinegar or lemon juice (water) are designed never to mix. It needs the eggs to act as a bridge and form a stable, uniform sauce. This is a delicate balance because everything from the temperature, length of cooking, and the ratio of ingredients can affect the stability.
If the sauce looks like scrambled eggs rather than a thick, velvety sauce, it's game over, sadly. The eggs are overcooked and there is no coming back from this. But if the sauce has separated into oil and water components and looks watery and grainy, it is still salvageable.
What you need to do is start with a new batch or emulsifier (i.e. beaten egg yolk and vinegar or lemon juice) and then slowly whisk the broken sauce into the emulsifier. This works only if you have spare ingredients — and remember to thin out the sauce with some water.
Handy tips to making egg-based sauces
Since the definition of insanity is doing the same thing repeatedly and expecting a different result, try to work out why the sauce might have split so that you can improve your technique. Was the sauce overheated? Was it overmixed?
There are a few handy tricks from the experts. Writing in The Guardian, food writer Nigel Slater's tip for making hollandaise sauce is to avoid excess heat and whisk all the ingredients in a "heatproof glass bowl over lightly simmering water rather than make it directly in a saucepan." Similarly, an often repeated tip for making stable mayonnaise is to drip the oil into the egg yolks drop by drop at first, because rushing it will cause it to split. When the mixture thickens, you can speed up the process.
These suggestions sound like culinary tips but really it is a science experiment that allows you to also enjoy eggs Benedict and hollandaise sauce at home.