Temper.
What it is. Gradually raising the temperature of a cold ingredient (eggs, cream, butter) by whisking in small amounts of a hot liquid, preventing shock-cook or curdling. The core move for custards, hollandaise, carbonara, béarnaise, and crème anglaise. Without tempering, the eggs scramble or the sauce breaks the moment they meet heat.
Why It Works — The Science
Proteins in eggs and dairy coagulate above specific thresholds: egg yolks thicken at ~150°F but scramble at ~180°F. Dropping cold eggs into hot liquid causes localized temperature spikes that curdle the exterior of the yolk before the center warms. Streaming hot liquid into the cold egg mixture slowly — while whisking — raises the whole batch's temperature evenly, below the scramble threshold.
How To Execute
- Warm the cold ingredient in a separate bowl. Eggs, cream, or butter — pulled out of the fridge, set in a bowl wide enough to whisk in.
- Off heat, ladle ¼ cup of the hot liquid into the cold, whisking. The stream should be thin and steady. The whisk never stops.
- Repeat 2–3 more times until the cold has doubled in volume and feels warm to the back of your hand.
- Pour the tempered mixture back into the hot pan while whisking. Steady stream, constant motion, no pause.
- Keep below the scramble threshold. 150–160°F for yolks; sub-simmer for dairy. A thermometer earns its keep here.
- If you see curd — strain immediately. A fine-mesh sieve can sometimes rescue the sauce before the texture collapses further.
Failure Modes
- Poured cold into hot. Scramble. The eggs seize on contact.
- Poured too fast. Curdle. The stream outpaced the whisk's ability to disperse the heat.
- Stopped whisking. Curdle. Static yolk in hot liquid = localized spike.
- Exceeded threshold. Scramble. Unrecoverable — start over.
Pair With
Tempering is the precondition for every egg-thickened sauce — hollandaise, béarnaise, carbonara, crème anglaise, lemon curd, sabayon. Also used for chocolate (different technique, same concept: raising temperature in controlled stages to prevent the proteins or crystals from breaking).