Wash the potatoes and cook in boiling water for about 20 minutes. Meanwhile clean, wash and drain the cauliflower and cut it into about 12 slices. Whisk eggs in a deep plate. Turn the cauliflower slices one after the other in flour, eggs and breadcrumbs.
For the salad, whisk stock, vinegar, 3 tablespoons of oil and mustard. Season with salt and pepper. Peel onion and cut into fine strips. Wash, clean and slice the radishes. Clean, wash, shake dry and cut into wide strips.
Quench the potatoes cold and let them cool down. Then peel and dice. Mix the salad ingredients carefully. Heat 4 tablespoons of oil in a frying pan and fry the cauliflower slices for about 4 minutes on each side.
Arrange salad and cauliflower on plates.