Boil the potatoes with the skin in a lot of water, to which the cumin has been added, in about 20 minutes. If you don't like cumin, you can leave it out.
In the meantime, prepare the marinade: cut the onion into very small pieces and heat the broth in a pan or small pot. Add the raw onion, as well as the mustard, vinegar, salt, pepper and sugar. Mix everything well so that the ingredients dissolve.
Take 2 tablespoons of cucumber water from the cucumber jar and add this too. Season the broth well. Let everything boil for 3 minutes. Remove from heat.
When the potatoes are done (pierce the center of the largest ones with a small knife to check) drain the water and peel the potatoes. Note: If you use a fork, prick the hot potatoes with it and hold them, you can peel them perfectly all around. Or use a clean kitchen towel.
Cut them into thin slices or cubes and pour the hot broth over the potatoes while they are still warm. Mix them carefully with two spoons and now leave the potato salad covered at room temperature for at least two hours.It tastes best if the salad is allowed to marinate overnight.
The potatoes should have absorbed the marinade almost completely. If not, pour off the rest. The salad should be moist, however.
Before serving, wash the kitchen herbs (for example, parsley, chives, oregano, dill or basil), pat dry, chop finely and mix with the salad. Now also cut the pickeled gherkins into thin slices and add them, pour the oil in the salad and mix well.