Harden the eggs for 10 minutes in a pan of lightly vinegared boiling water. Refresh them under cold water. Shell them.
Take the yolks. Mash them in a bowl using a fork. Add the mustard. Pour in the oil little by little, building up the sauce like you would make mayonnaise. Add the vinegar. Add salt and pepper.
Chop the egg whites and mix them with the sauce at the same time as the chopped chives.
Tips and advice for Mayonnaise with hard-boiled eggTo whip up an aioli or mayonnaise without difficulty, by hand or with an electric appliance, take care to remove the egg in advance so that it is at the same temperature as the ‘oil.
To make up for mayonnaise, take 1 spoonful and pour in 1 tbsp. tablespoons of boiling vinegar. Start adding the mayonnaise again, replacing the oil with the sauce, while whisking.