The liver is washed and dried. Cut into slices and then into cubes 1 cm. Sprinkle pepper but no salt. Heat butter in a large pan, add a little sunflower oil and slowly put the liver. Stir until pozaparzhi from all sides, taking care not fried. With latticed spoon out the liver, put it in a bowl and pour the cognac. In the fat from frying sauté chopped onion and mint. Gets cooked cous-Kusa in lightly salted water with 1 tbsp sunflower oil. Wash with lukewarm water, drained well and put in a pan with onions. Put it and the liver, salt and pepper. Stir and fry for another 5 minutes. If possible, do not wash the liver, just wipe with a damp cloth. The basic rule of the liver is not pre salts.