How to make mayonnaise

What an emulsion actually is

Oil and water do not mix. In mayonnaise they are forced to: the oil is broken into droplets so small they stay suspended, and each droplet is coated in lecithin from the egg yolk, which has one end that likes water and one that likes fat.

The yolk can only coat so much oil at a time. Add oil faster than it can be broken up and coated, and the droplets merge back together — the mayonnaise splits.

At the start there is very little emulsion to work with, so the oil must go in almost drop by drop. Once enough droplets exist, they help break up the incoming oil and it can be added much faster.

By hand, which is the way to learn it

1. Have everything at room temperature. Cold egg and cold oil emulsify reluctantly.
2. Put an egg yolk in a bowl with a teaspoon of mustard, a pinch of salt and a small splash of vinegar or lemon juice. Whisk to combine.
3. Sit the bowl on a damp cloth so it does not skate around the worktop. This is the single most useful practical tip.
4. Add oil a few drops at a time, whisking constantly, until the mixture visibly thickens and turns pale. This first stage is slow and it is the whole difficulty.
5. Once it has thickened, add the oil in a thin steady stream, still whisking.
6. If it becomes too thick to whisk, loosen it with a few drops of water, vinegar or lemon juice, then carry on.
7. Finish by tasting and adjusting salt and acid. Mayonnaise almost always needs more of both than expected.

Splitting, and how to fix it

• It splits because the oil went in too fast, or the ingredients were too cold, or the yolk was overloaded.
• The fix: start again in a clean bowl with a fresh egg yolk, or a teaspoon of mustard, or a spoonful of warm water.
• Whisk the split mixture into it drop by drop, exactly as you added the oil originally. It re-emulsifies.
• This works every time and no mayonnaise ever needs throwing away.
• A blender or stick blender is more forgiving because it breaks the oil up mechanically, and a stick blender in a tall jar makes mayonnaise in thirty seconds.
• One yolk carries a lot of oil — considerably more than most recipes use — but there is a limit, and exceeding it splits it.
• Egg safety — raw egg in an uncooked sauce is a food-safety matter, and the Food Standards Agency is the authority on which eggs are suitable and for whom.

Choices that change it

Oil

A neutral oil — rapeseed or sunflower — for a clean mayonnaise. Olive oil alone turns bitter when blitzed, so use it as part of the total or add it by hand at the end.

Mustard

Not just flavour. It is an emulsifier in its own right and makes the process considerably easier.

Acid

Lemon juice for a lighter mayonnaise, wine vinegar for a sharper one.

Whole egg

Works in a blender and gives a lighter, paler mayonnaise. Yolk alone gives a richer one.

Aioli

Traditionally garlic pounded with salt and emulsified with oil, sometimes without egg at all. The garlic mayonnaise sold as aioli is a different thing.

Common questions