Mayonnaise

Mayonnaise is a cold, creamy sauce made by slowly whisking oil into egg yolk, with lemon juice or vinegar, salt and often mustard. The yolk holds the oil in tiny droplets, so a liquid turns into a thick, spoonable sauce. It is a base for many other sauces, such as aioli, tartar sauce and remoulade.

How to do it

For about 250 ml (1 cup):

1. Put 1 egg yolk at room temperature, 1 teaspoon Dijon mustard, 2 teaspoons lemon juice or vinegar and a pinch of salt in a bowl. Set the bowl on a damp towel so it does not slide.
2. Whisk in 200 to 250 ml (about 1 cup) of neutral oil, drop by drop at first.
3. When it thickens and turns pale, add the oil in a thin, steady stream, whisking all the time.
4. Taste and add more acid or salt. Thin with a teaspoon of water if it is too stiff.

With an immersion blender, you can use a whole egg. Put everything in a narrow jar, let the oil settle on top, press the blender to the bottom, switch it on, and slowly lift it.

Why it works

Mayonnaise is an emulsion, oil spread as droplets in a small amount of water. Lecithin and proteins in the yolk, plus mustard, coat each droplet and keep them from merging.

How to store it

Homemade mayonnaise with raw egg keeps in the fridge for 2 to 3 days. Use pasteurized eggs for anyone pregnant, very young, elderly or with a weak immune system. Store-bought mayonnaise is made with pasteurized eggs and keeps longer once opened, as the label says.

Common mistakes

• Adding oil too fast at the start, so it splits into a greasy liquid. To fix it, whisk a new yolk in a clean bowl and slowly whisk the broken mayonnaise into it.
• Using only strong extra virgin olive oil, which can turn bitter.
• Using a cold yolk, which emulsifies less easily.

In recipes

Recipes often ask for "mayo" in dressings, coleslaw, potato salad and sandwiches. Japanese-style mayonnaise uses only yolks and rice vinegar and tastes richer.