Wash the duck breast and pat dry. Heat 1 tablespoon of oil in a frying pan. Fry the duck breast on both sides for about 5 minutes. Season with salt and pepper. Cook for about 15 minutes and let it rest in aluminium foil.
In the meantime peel the oranges so that the white skin is completely removed. Remove the fillets from the parting skins with a sharp knife. Squeeze the juice out of the parting skins. Peel onions and cut into rings. Clean and wash salads. Pluck radicchio into bite-sized pieces. Cut avocado in half, remove stone. Cut out fruit fish with a small ball cutter and sprinkle with lemon juice. Mix vinegar and orange juice with mustard, salt, pepper and sugar. Add 3 tablespoons of oil.
Pluck radicchio into bite-sized pieces. Cut avocado in half, remove stone. Cut out fruit fish with a small ball cutter and sprinkle with lemon juice. Mix vinegar and orange juice with mustard, salt, pepper and sugar. Add 3 tablespoons of oil. Mix prepared salad ingredients and marinade. Cut the duck breast into slices and serve