Q: Why do my sauces sometimes fall apart?

AskFN: When you're making egg-based sauces like hollandaise or mayonnaise, you're trying to get egg yolks and fat to blend. In order for that to happen, you have to add the fat as slowly as possible, whisking constantly so the sauce emulsifies (that is, looks thick and creamy). If, for whatever reason, the sauce begins to look grainy (there's liquid on top and solids on the bottom), your sauce is broken; but, you don't have to throw it out. There's an easy way to fix it.

Add a splash of warm water (a small one, no bigger than a teaspoon) to an empty bowl, and slowly begin beating the broken sauce into it. Start with a few tablespoons, and add more of the broken sauce gradually, starting only after the sauce already in the bowl is emulsified. If that doesn't work, add another egg yolk to the bowl. You'll have to adjust the other ingredients accordingly, and you'll have more sauce than you intended, but you'll have saved dinner.

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Recipes Mayonnaise Hollandaise