The panino con arrosticini takes Abruzzo's signature skewer and strips it into bread. Arrosticini are small cubes of mutton or castrato threaded tightly onto thin wooden sticks and grilled fast over a long narrow brazier, the fornacella, until the fat chars and the meat stays just pink. Eaten off the stick they are a thing of their own; pulled off into a split roll they become a sandwich whose entire character comes from the grill, not from any assembly. The defining move is the stripping: the meat is slid off the skewer directly into the bread while it is still spitting, so the panino is really a delivery vehicle for something that was finished seconds earlier over coals.
The craft is the fire and the speed. Mutton is fattier and stronger than lamb, so the skewers are cooked hard and close to the heat to render and char the fat while keeping the small cubes from drying, and they go into the bread the moment they come off, because arrosticini that have cooled lose the thing that makes them. The bread is the traditional pane casereccio, a sturdy Abruzzese country loaf, rubbed with oil and sometimes warmed on the same grill so it takes the fat without going slack. The classic dressing is almost nothing: oil, salt, maybe the bread alone, because the smoke and the rendered mutton fat are the whole flavour and a sauce would only argue with them. It is eaten standing, at the brazier, fast.
The variations stay Abruzzese and stay on the same coals: the version rubbed with olio santo, the chilli oil of the region, the one that adds grilled peperoni or a smear of the local pecorino, the build on pane casereccio against a soft roll. Each of those is a different turn on the same skewer and fire, and each deserves its own article rather than being crowded in here.