Wash the potatoes thoroughly and boil for about 15 minutes. Peel and halve the onion and cut into strips. Cut Leberkäse into pieces. Clean and wash the pointed cabbage and cut it into approx. 2 cm wide strips.
Blanch the pointed cabbage in salted water for 3-4 minutes, then rinse under cold water and drain well. Wash, clean and quarter the radishes. Heat 2 tablespoons of oil in a large pan.
Cut the potatoes in half. Fry the potatoes, onion strips and Leberkäse all around for about 5 minutes until golden brown. Add the radishes after 2-3 minutes. Heat 1 tablespoon of oil in a 2nd frying pan. Fry the pointed cabbage strongly in the pan, then add to the potatoes.
Season the potato roast with salt and pepper.