Boil the Potatoes: Boil the potatoes in salted water until tender.
Prepare the Onion and Pickles: Peel and dice the onion. Dice the pickles. Sauté the diced onion in a pan with some butter until translucent.
Make the Mustard Broth: Add mustard and vegetable broth to the pan with the onions and bring to a brief boil.
Prepare the Potatoes: Drain the cooked potatoes and let them cool for about 10 minutes. Slice the potatoes and mix them with the mustard vegetable broth, chopped parsley, and pickle cubes. Season with salt, pepper, and a bit of white vinegar.
Prepare the Schnitzel: Season the schnitzel with salt, pepper, and a bit of lemon juice. Bread each schnitzel in the following order: flour, egg, breadcrumbs.
Fry the Schnitzel: Warm a pan with enough oil on low heat. To check the optimal temperature, add a bit of breadcrumbs to the oil; once the oil starts forming small bubbles, the temperature is right. Fry the schnitzel until golden brown on both sides. Remove the schnitzel from the pan and let the excess oil drain on a paper towel.
Serve: Arrange the schnitzel on a plate with the potato salad. For an even better taste experience, squeeze lemon juice over the schnitzel before serving.