A sauce based on eggs can be temperamental, breaking down from a thick, creamy mixture to a thin liquid with grainy curds in the blink of an eye. Mayonnaise and hollandaise are both emulsions of egg yolks, but when they separate--unlike Humpty Dumpty--you can put them back together again.
Instructions
Saving a cold emulsion
1. Stop adding oil as soon as you see the mixture loosen and turn grainy. Adding oil too quickly to an egg yolk or forcing more oil than it can hold will break an emulsion such as mayonnaise.
2. In a separate bowl, whisk together a fresh egg yolk and 1 tbsp. lemon juice.
3. While whisking constantly, drizzle the broken mixture very slowly into the new yolk. If you're using a blender, transfer the mixture back into the blender jar.
4. Continue whisking or blending in more oil slowly until you obtain the desired consistency. Unrefined oils such as extra-virgin olive oil tend to separate easily, so use pure olive oil or another refined oil to make a more stable mixture.
Saving a warm emulsion
5. Prepare warm egg-based mixtures like hollandaise or be'arnaise sauce in a double boiler over hot (barely simmering but not boiling) water to help prevent breaking and curdling. Whisk in melted butter slowly. Take care not to add more than the yolks can hold.
6. A thin line of oiliness around the edge of the sauce is an early warning that the sauce may separate. At this point, you can try saving it before it actually breaks. Immediately remove it from the heat. Slowly whisk in 1 tbsp. cold water or cream.
7. Once the sauce breaks completely, you'll need to add a fresh egg yolk to rebind the liquids. In another bowl, whisk together 1 egg yolk and 1 tbsp. cold water or cream.
8. While whisking constantly, very slowly drizzle the broken, still-warm sauce into the new egg mixture.
9. Return the sauce to the double boiler. Whisk constantly until it thickens to the desired consistency.
Tags: bowl whisk, bowl whisk together, cold water, cold water cream, desired consistency, double boiler