Osteria Rosso di Vino - the single best restaurant of our Sicily trip. I'm embarrassed to say that I don't remember what I had, except that it was exceptionally delicious.
Casa Gioli - again, I don't remember what I had, but it was really good. Another keeper.
Osteria Nero d'Avola: this was memorable even before we ate. As we were looking at the menu outside, the owner told us to ignore the menu and come into the kitchen, as he described and showed us the fresh produce and sea creatures (some still alive) he had gotten from the markets that day. My fish (alalaguna, apparently related to tuna) was delicious. They debone all the fish tableside, which makes for quite a show if several orders come out at once. And dessert was made with citrons, which are like large lemons but with a sweet skin - wonderful.
Villa Zuccaro Pizzeria: very good pizza (I know it's hardly a Sicilian speciality, but we wanted a faster meal for our last night).