Mayonnaise can be made very quickly and easily in a food processor. Although there is less risk of curdling and separating when making by machine - the speed helps to emulsify the egg and oil - a whole egg is used rather than just egg yolks, because the white is needed as a stabilizer. The combination of egg white and speed will give a fresher and lighter mayonnaise than that made by hand.
Put 1 tbsp Dijon mustard and 1 whole egg in the machine; work until blended.
While machine is running, add 250 ml olive oil in a thin steady stream.
When the mixture begins to thicken, add 2 tsp vinegar and salt and pepper to taste. Work until blended.
With the machine running, add 250 ml vegetable oil, increasing the flow once the mayonnaise becomes pale. Check seasoning. Makes about 650 ml.