Lay a tea towel on the work surface and stand a mixing or salad bowl on the towel.

In the bowl, combine the egg yolks, mustard and a little salt and pepper.

Mix with a whisk.

Pour in the oil in a thin, steady stream, whisking continuously.

When it is all incorporated, whisk more vigorously for 30 seconds to make a thick, glossy mayonnaise, then add the hot vinegar or cold lemon juice.

Adjust the seasoning with salt and pepper.

If you prefer, you can replace some of the groundnut oil with olive oil, but do not use more than one-quarter, as olive oil has a very pronounced flavour.

For a creamier mayonnaise, mix in 2 tablespoons double cream after adding the warm vinegar or cold lemon juice.

The mayonnaise can be kept at room temperature, covered with cling film, until ready to use.

However, it is not wise to keep it for more than a few hours unless you use pasteurized eggs.

Don't serve mayonnaise in a silver sauce dish: it will oxidize quickly and turn it black.