Heat oil (about 100 ml) in a frying pan and onion cut into discs. Fry until nicely golden and caramelized. Add salt to taste. If onions stick to the pan, put a little water CE. Once the onion is golden brown and transparent is ready. Maha from heat, remove from the pan and put in a separate container. In the same pan add a little more olive oil (50-70 ml), fillets, pepper and basil fry each side for about 30 seconds. When meat is almost ready, add balsamic vinegar. Strong taste will decrease by cooking and will become a pleasant thick, sweet sauce. After about 15 minutes the onion return to pan. Add savory. So everything simmer for another 5 minutes.