Oil and water do not mix. Everyone knows this. Emulsification is the process of forcing them to mix anyway, using an ingredient that acts as a bridge between the two. Egg yolk is the most common bridge. Mustard works as well. Without one of these, your sauce separates into an oily puddle within minutes.
Wednesday afternoon, hollandaise attempt number three
Geoffrey, a former civil engineer in Hobart, spent two afternoons watching his hollandaise split before he understood what was going wrong. He was adding butter too fast. Emulsification requires patience: the fat must be introduced slowly, in small amounts, while the egg yolk is still warm enough to hold everything together. Rush it and the sauce breaks.
The decision point is temperature. If the yolks get too hot, they scramble. Too cool, and they cannot absorb the butter. Most home cooks work around 60 to 65 degrees Celsius, which is warm to the touch but not scalding. A thermometer removes the guesswork entirely.
- Whisk yolks with a splash of water over gentle heat until slightly thickened
- Remove from heat, add butter one tablespoon at a time
- Whisk constantly between each addition
- Season at the end, not the beginning
Once Geoffrey slowed down and used a thermometer, his hollandaise held together consistently. The technique did not change. His timing did.