For the potato salad, first cook the potatoes in salted water for 20-25 minutes, drain and steam. Peel, cut into thin slices, place in a large stainless steel bowl. Finely dice the onions.
Mix vinegar with 400 ml water, sugar, one teaspoon salt, pepper and mustard until smooth, add onions. Boil the broth for two minutes and pour over the potatoes. Add oil. Mix the ingredients carefully. Put the bowl on the hot stove. Cook lettuce at high temperature for 2- 3 minutes, shaking baking dish 2-3 times.
Finely dice the bacon, fry in a frying pan until crisp, drain in a sieve and fold into the lukewarm potato salad.