Rhenish potato salad

Ingredients for 5 servings:

• 1 ½ kg potatoes, medium-sized
• 2 onions
• 500 ml oil, neutral
• 1 tbsp mustard
• 1 tsp vinegar
• 1 pinch(s) of sugar
• salt and pepper
• 5 egg yolks
• 5 gherkins
• some condensed milk

Instructions

Working time approx. 30 minutes; Rest time approx. 7 hours; Total time approx. 7 hours 30 minutes

Boil the potatoes with their skins on the day before. Peel them the next day and cut them into small pieces. For the mayonnaise, only the egg yolks are needed; place them in a bowl. Caution! The egg yolks and oil must be at the same temperature, otherwise the mayonnaise will curdle. Add the mustard, vinegar (neutral flavor), a pinch of sugar, salt, and pepper to the egg yolks. Mix everything with a whisk. Then add the oil in a thin stream, stirring constantly. It should reach a thick consistency. Then thin the mayonnaise with a little canned milk. Season again generously with salt and pepper (the sauce should taste slightly salty, as the potatoes will absorb some of it). Finely chop the onions and cut the gherkins into small or large pieces. Add both to the sauce. Let the sauce sit in the refrigerator for half an hour. Then mix with the potatoes and refrigerate for at least 6 hours. Season again with salt and a little pepper about half an hour before eating.