Step 1

Whizz the egg yolks, mustard and vinegar or lemon juice in a food processor, then add the oil in a confident, steady stream äóñ you need keep up with the speed of the blades. It is ready when the blades leave a visible trail through the mayonnaise. Season to taste.

Step 2

To make it by hand, it is best to get someone to help. One of you holds the bowl steady and whisks, while the other adds the oil in a gentle, continuous drizzle. Season to taste. Note: if it curdles, remove it from the processor or bowl and set aside. Add 1 egg yolk and whizz or whisk briskly, slowly adding back the curdled mayo. The new egg should bring it back together.