For the salad, wash the potatoes and cook in water for about 20 minutes. Peel and finely chop the onion. Heat 2 tablespoons of oil in a frying pan. Fry the onion until transparent. Deglaze with 150 ml water and vinegar. Bring to the boil, stir in broth and simmer for about 2 minutes. Drain the potatoes, let them cool down briefly, peel them and cut them into slices directly into the hot broth. Let stand for at least 1 hour.
For the fried chicken, rinse chicken legs and pat dry. Finely crumble the chips and mix with breadcrumbs. Whisk the eggs in a deep plate. Season with salt and pepper. Heat 1 l oil in a wide pot to approx. 170 °C. Turn the legs one after the other first in flour, then pass through the eggs and finally turn in the chip mixture. Immediately deep-fry in hot oil in portions for 6-8 minutes until golden brown (see tip). Remove with a skimmer and let it drip off on kitchen paper. Then place on a baking tray lined with baking paper. Bake in a preheated oven (electric cooker: 180 °C/circulating air: 160 °C/gas: see manufacturer) for approx. 30 minutes.
Wash the cucumber, slice or cut it into thin slices and fold into the potato salad with the horseradish. Season to taste with salt and pepper. Serve with the fried chicken.
TIP: Fry the legs in hot oil immediately after breading, otherwise the crust will not be really crispy.