Emulsification

Why it works

Egg yolk, mustard, starch from pasta water, or vigorous tossing creates a network that suspends fat droplets in water. Heat helps if it is gentle and ruins you if it is not: carbonara on a ripping-hot pan is scrambled eggs, not sauce. The gloss you want is tiny droplets, not a slick of oil floating on wet pasta. That is why Roman kitchens talk about pasta water as an ingredient, not a drain.

How to do it

1. Start with a binder: yolk, starchy pasta water, mustard, or a reduced stock with body.
2. Add fat gradually, or toss off the heat so eggs do not scramble. Residual heat is usually enough.
3. Move the food. A still pan splits; a tossed pan holds.
4. If it splits, add a splash of warm water and whisk or toss hard. Sometimes a fresh yolk will pull it back.
5. Serve immediately. Emulsions wait for no one, and a minute under a lamp will break a carbonara.

Common mistakes

• Carbonara on a ripping-hot pan — scrambled eggs, not sauce.
• Adding oil all at once to a mayonnaise.
• Using pasta water that was never salted, then wondering why the sauce tastes flat.
• Letting grated pecorino hit a dry, scorching pan so it clumps into plastic.

Recipes using this

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