Wash potatoes thoroughly and cook in boiling water for about 20 minutes. In the meantime dice cucumbers. Clean and wash spring onions and cut them into rings. Mix vinegar, mustard, apple juice, salt, pepper and sugar.
Beat olive oil into it. Drain the potatoes, rinse and peel. Cut the potatoes into thin slices. Mix with cucumber and spring onions. Pour vinaigrette over them. Mix the salad loosely and cover and leave to stand.
Wash the fish, dab dry and cut into 12 slices. Sprinkle with lemon juice and season with salt and pepper. Mix herb mixture and breadcrumbs. Heat oil in a pan. Turn the fish slices in the herb breading, press lightly and fry on medium heat for about 2 minutes on each side.
Put the salad on a plate and arrange the fish slices on top. Serve garnished with parsley and lemon wedges.