1. In a pan, heat the olive oil. Add the 4 slices of veal liver and cook, over high heat, 2 minutes on each side. Remove the liver slices and keep them warm.
2. In the pan, add the vinegar and let it reduce for 1 minute. Add the onions and cook, stirring, for 3 minutes. Add the sugar and let it caramelize for 1 minute.
3. Add the beef broth. Return the veal liver to the pan. Add the fruits and let the liquid reduce by half.
4. Serve the slices of liver covered with the sauce.