Hollandaise is the kind of sauce that only a dieter or cardiologist could possibly dislike. It's made primarily of butter and egg, but somehow contrives to taste even richer than those two main ingredients. It makes an elegant complement to steamed asparagus, or a decadent breakfast when poured over eggs Benedict. However, it can be slightly tricky to make, and novices are sometimes intimidated -- or frustrated -- by its tendency to separate, or "break." Luckily, that misfortune is easily avoided and easily mended.
Learning to Mingle
It's proverbially true that oil and water don't mix, but a Hollandaise sauce -- like mayonnaise and many others -- does exactly that. Most recipes contain a splash of water-based lemon juice or vinegar, while the egg yolk and the butter itself contain both water and fats. The trick is to keep them in an emulsion, with the globules of fat evenly dispersed throughout the relatively small quantity of water. The egg yolk is your ally in that quest, filled with emulsifiers such as lecithin that act as matchmakers, bonding water molecules and fat molecules together. The whole trick to making Hollandaise is to not give those emulsifiers more work than they can handle.
The Classic Technique
The classic technique for making Hollandaise requires a heatproof mixing bowl, and a pot or pan of simmering water. Break the egg yolk into your mixing bowl and whisk it until it's frothy, then add the vinegar or lemon juice and a pinch of salt. That provides the liquid base for your emulsion. Place your bowl over the hot water and begin whisking in small cubes of cold butter. Whisk until each one is fully incorporated before adding the next. Butter itself is an emulsion of milkfat and water, so if you add it in small pieces and whisk vigorously, it will form a smooth, rich Hollandaise.
Of course, it doesn't always go smoothly. If the butter is too soft, it might melt faster than it can be incorporated into the sauce. The pieces might also be too large, or you might not have whisked the earlier pieces thoroughly enough. Whatever the cause, the symptom is the same. You'll see threads and pools of melted butter spreading through an increasingly lumpy-looking sauce. When that happens, add a few drops of cold water and whisk vigorously. Increasing the liquid lends your sauce the ability to emulsify more butter, reforming the emulsion and fixing your problem.
Repairing the Damage
If the water trick doesn't fix your sauce, it's time to bring out the big gun. Separate a fresh egg yolk into a second mixing bowl, and whisk it with a few drops of lemon juice until it's frothy. Place it over the hot water, and begin adding your failed sauce to the new egg in very small increments. Whisk the sauce vigorously to create a new emulsion, taking care not to go too quickly. Adding a new yolk "doubles down" on your emulsifiers, and increases the available liquid, so the new emulsion is sturdier than the original. Once you've added all the failed sauce, whisk in any remaining pieces of cold butter. Taste the finished sauce and adjust the seasoning if necessary.
- On Food and Cooking: The Science and Lore of the Kitchen; Harold McGee
- On Cooking: A Textbook of Culinary Fundamentals; Sarah Labensky et al
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