Sarde in Saor

Sauté the sliced onions and let them sweat in olive oil, making sure they do not brown. When they turn translucent, add the vinegar, salt and pepper. Simmer for about 40 minutes, they should be ready when all the liquid has evaporated. Clean and butterfly the sardines, remove the backbones, coat them in flour and fry in abundant oil. Lay them in kitchen paper so as to drain off as much oil as possible, then layer the sardines with the hot onion mixture, adding also the rasins and pine nuts. Leave for at least 24 hours before serving them, keep them in the fridge. Serve them with grilled white polenta.