Wash the livers and drain out the water. Cut them into pieces. Cut the onions into crescents and the garlic and mushrooms into slices. Roll the livers in flour and fry them in very hot oil. Fry the onions separately until golden and add the mushrooms. Fry 3-4 more minutes.
Combine the tomato paste with 3 tablespoons water and black pepper. Add them to the onions and allow the water to boil off.
Pour the onions to the ready livers. Leave for a little bit on the fire, salt and finally sprinkle with parsley.