Mayonnaise split

The rescue

This works nearly every time.

1. Take a clean bowl and put in one fresh egg yolk, or a teaspoon of mustard, or a tablespoon of warm water.
2. Whisk it briefly.
3. Now add the broken mayonnaise to it, drop by drop at first, whisking constantly — treating the broken sauce exactly as if it were the oil.
4. Once it starts to thicken and hold, you can add the rest in a thin steady stream.
5. You will end up with slightly more mayonnaise than you started with, and nobody will be able to tell.
6. A stick blender in a narrow jug is the fastest alternative: put the broken mixture in, insert the blender to the bottom, and blitz without moving it for ten seconds before slowly lifting.

Why it split

• Oil added too fast at the start. The yolk can only take so much at once. The first few tablespoons are the critical ones and must go in drop by drop.
• Too much oil for the yolk. One yolk holds roughly 200ml of oil comfortably. Push past that and it breaks.
• Cold ingredients. A fridge-cold yolk and cold oil emulsify poorly. Everything at room temperature.
• Not enough whisking. The emulsion is made by shearing the oil into droplets small enough to stay suspended. That takes vigorous work.
• Adding acid too early or too late. A little at the start helps; a lot dumped in at the end can break it.

Making it so it holds

1. Bring the egg, oil, mustard and lemon to room temperature.
2. Whisk the yolk with a teaspoon of Dijon mustard and a squeeze of lemon. Mustard is a powerful emulsifier and makes the whole thing far more stable.
3. Add the oil literally drop by drop to begin with, whisking hard. Do not hurry this — it is a minute of patience that decides the outcome.
4. Once it visibly thickens and lightens, increase to a thin steady trickle.
5. Stop when it is as thick as you want. If it becomes too stiff, whisk in a teaspoon of warm water.
6. Season at the end with salt and more lemon or vinegar.

Choices that matter

Oil

A neutral oil — rapeseed, sunflower, groundnut. All extra virgin olive oil gives a harshly bitter mayonnaise, because whisking shears the oil and releases bitter compounds. Use a small proportion at the end if you want the flavour.

Mustard

Not optional if you want reliability. It emulsifies and it seasons.

Whole egg

A whole egg makes a lighter, more stable mayonnaise and is what a stick blender wants.

Acid

Lemon for brightness, white wine vinegar for a cleaner sharpness.

Aioli

Traditionally garlic pounded with oil and no egg, which is much less stable. Most modern versions are mayonnaise with garlic.

Common questions