Place the pike-perch fillets skin side down in the not-too-hot fat and roast leisurely, basting several times. Briefly sauté the diced cucumber in butter. Pour in 2 tbsp of moderate soup, add the potato cubes, lightly bubble with cream for about 2 minutes. Season with sour cream, mustard, chopped cayenne pepper, dill, salt and juice of a lemon.
For the potato chips, remove peel from potatoes and cut into thin slices. Put potato slices in water for 10 minutes, then dab well. Heat enough oil in a deep frying pan, deep-fry potato slices to crispy chips. Later take out and drain. Only now season with salt.
Spread mustard gherkins evenly on plates, place fried pike-perch fillets on top. Garnish with potato chips.
Tip: Instead of clarified butter, you can also use butter in most cases.