Wash the meat and dab dry. Halve meat lengthwise. Heat oil in a large pan. Fry the meat for approx. 6 minutes, turning it over. In the meantime peel onion and cut into rings.
Cut the mozzarella into slices. Drain the tomatoes in a sieve. Remove the meat and season with salt and pepper. Wash the salad and shake dry. Season mayonnaise with curry. Cut the tomatoes into pieces.
Cut open the buns. Spread the lower halves of the rolls with mayonnaise. Cover with lettuce, chicken filet, mozzarella, tomato and onion, sprinkle with pepper. Place the upper roll half on top.