Hard-Boiled Egg Yolks Are Key For An Easy-To-Make Hollandaise Sauce
Hollandaise sauce is the perfect sauce to put on eggs benedict, poached eggs, or roasted asparagus. But, let's be honest, it isn't the easiest thing to make. Though it comes together with just three simple ingredients — egg yolks, clarified butter, and an acid such as lemon juice or vinegar — there's a lot of room for error. Use butter that's a little too hot, for example, and the eggs could easily curdle. Use the wrong ratio of ingredients, and the mixture could start to separate.
The unstable nature of the classic French sauce is reason enough to resort to the jarred or powdered kind. But there's actually a shortcut that can make it easier to prepare from scratch. Instead of whisking raw egg yolks over a double boiler, simply hard boil them, then blend them up with the clarified butter and lemon juice until it turns into a sauce. Even though this method breaks the rules of a traditional hollandaise, there's no risk of accidental overcooking, and it looks and tastes nearly identical to the real thing.
How it works
If hollandaise sauce is so temperature sensitive, you might be wondering why it's possible to substitute raw egg yolks for hard-boiled ones. The short answer is that the conventional method relies on an emulsion, while the shortcut only mimics one. Hollandaise is made up of ingredients that naturally repel each other, so to combine them into a homogenous sauce, you have to emulsify them through whisking. This whisking essentially breaks down the egg yolk, butter, and lemon juice into tiny particles so they disperse more evenly, ultimately forming a cohesive sauce.
Though they do break down well, hard-boiled egg yolks can't be emulsified since emulsions can only form between liquids. Therefore, instead of combining them with the other hollandaise ingredients through heat and vigorous whisking, they have to be blended together. This doesn't technically result in a true hollandaise, but you'll still be able to serve the sauce in the same way.
The benefit of using hard-boiled egg yolks for hollandaise
Aside from being a more foolproof way to make hollandaise sauce, using hard-boiled eggs also has the advantage of being easier to reheat. The eggs in traditional hollandaise sauce are tempered, which means if you tried to reheat them, they'd curdle and ruin your sauce. You either have to settle for using it only once or carefully warm it up indirectly by letting the bowl sit in hot water. When you use hard-boiled egg yolks, on the other hand, you can just stick your sauce in the microwave because the eggs are already cooked.
For the same reason, hollandaise made with hard-boiled eggs is also more convenient because it can be made ahead of time. Traditional hollandaise by contrast can only be made an hour in advance at most because it separates when cool, and to maintain its integrity, you have to keep it warm and re-whisk it. This makes using hard-boiled eggs a more practical choice, even if it doesn't yield a "real" hollandaise.