Wash the potatoes thoroughly. Cover with skin and cook in boiling water for about 20 minutes. Drain and rinse with cold water. Spit them on a three-pronged potato fork or a cake fork or even on a baking tray.
Let the potatoes cool down.
Cut cold potatoes into approx. 1⁄2 cm thick slices and place in a large bowl.
Peel and finely dice the onions. Cut the rind off the bacon. Dice the bacon finely and fry it crisply in a pan without fat. Add oil to the pan. Add onions and steam for about 2 minutes.
Deglaze with vinegar and 150 ml water and simmer for 1-2 minutes. Stir in stock. Season with salt, pepper and mustard.
Pour hot broth marinade over the potatoes and fold in. Leave to infuse for at least 1 hour.
Wash the chives, shake dry, cut into small rolls and mix into the salad. Season potato salad with salt and pepper again.