Measure the oil into a small jug.
Separate the eggs.
Keep the egg yolk in a second bowl. For the second egg separate the egg yolk from the egg white in the same way.
Season the yolks with a pinch of salt.
Add the mustard to the egg yolks with a teaspoon.
Mix the egg yolks with the salt and mustard with a small whisk.
Add the oil, starting drop by drop, then in a thin stream, whisking constantly.
Keep whisking until the mayonnaise is thick and creamy. Squeeze the juice from half the lemon.
Mix 1-2 tbsp lemon juice into the mayonnaise to taste.
You can now use the mayonnaise to make other dishes such as remoulade or dressings, or serve as a dip for fries or crisps.