* ~ 1 kg of potatoes
* 1 onion
* salt and pepper
* 1 hard boiled egg yolk
* 150 ml oil
* juice from 1/2 lemon
* 1-2 tablespoons mustard
Boil the potatoes in their skins, in salted water. Boil until the fork fits well in the potato.
For the mayonnaise , mix the crushed egg yolk with a little salt and a tablespoon of mustard. Stir continuously with a wooden spoon, putting a little oil at the beginning. When it starts to bind, sprinkle with a little cold water and continue with the oil. After finishing the oil, add the lemon juice and mix. Depending on the taste, you can also add lemon juice and / or mustard.
Boiled potatoes are passed under a stream of cold water, peeled and cut into cubes. Put in a bowl, then add finely chopped onion (or julienne cut, as desired), salt and pepper to taste, beaten egg whites with a small mesh and finally mayonnaise. Mix lightly until smooth.
It can be served as such or as a garnish for a steak.