Wash and trim the livers, removing any icky membrane and discolourations, and cut into 2.5 cm (1 in) pieces, Heat olive oil, add garlic, and cook for 2 minutes. Add onion and cook until soft. Add livers, rosemary and sage, and cook, stirring, until livers are almost cooked, about 3 minutes.
Remove livers, turn up heat, add wine, and allow sauce to bubble and reduce. Add tomato passato o