The onion, peel, cut in half and then quarter. If you only get large red onions, just cut them to a bite-sized shape but don`t cut them too small, otherwise they would overcook.
Sweat the onions in the olive oil with the sage for 1-2 minutes. Deglaze the whole thing with balsamic vinegar and red wine. Add the honey and let everything simmer for 5 minutes. Finally, season with salt, pepper and, if necessary, with peperoncini (I like to eat very spicy myself, but I am very careful with the spiciness of this dish).
After cooking, transfer the onions to another container and let them steep for at least 4 hours (but 24 hours are best, as the taste only develops gradually). Right after cooking, the onions are still pretty tasteless.
I like to serve it all on rocket and spread parmesan over it. Then add white bread and the Italian starter is perfect.
Otherwise you can eat it as a side dish to steaks - but there is no limit to your imagination.