Wash the potatoes and cook in boiling water for 15-20 minutes. Then rinse with cold water, peel and leave to rest. In the meantime clean, wash and cut leek into fine rings. Cut potatoes into slices and mix with leek. Boil up apple juice and vinegar. Season with salt, pepper and sugar.
Pour over while still hot. Clean the radicchio, cut into quarters and cut it up to the stalk. Wash the chicken filet and cut into 1 cm cubes. Wash apple, cut out core. Cut the flesh into fine slices or wedges. Heat 1 tablespoon of oil. Fry the chicken cubes until crispy. Season with salt and pepper and take out. Add 1 tablespoon of oil to the frying fat. Heat apple slices in it, turn once and sprinkle with lemon juice. Bring to the boil briefly, remove the apple slices and drizzle the gravy over the potatoes as well. Fold in the radicchio, season to taste again.
Fry the chicken cubes until crispy. Season with salt and pepper and take out. Add 1 tablespoon of oil to the frying fat. Heat apple slices in it, turn once and sprinkle with lemon juice. Bring to the boil briefly, remove the apple slices and drizzle the gravy over the potatoes as well. Fold in the radicchio, season to taste again. Sprinkle with the chicken croutons. Serve the salad with the apple slices
30 minutes waiting time