It is commonly believed Italians think about animals as far as they are good to eat: I cannot deny there's some truth in this... So, Sicily is a Paradise for tuna-fish lovers: forget about the canned stuff, it has no comparison at all with what you may experience in Sicily, where tuna-fish capture is an old tradition (now it disapperaed, because they didn't know about over-fishing....) carried on in the "tonnara" and culminating with a peculiar action called "mattanza". Nowadays, tuna-fish is no more as abundant as it used to be, but mr. Antonino Serio prepares wonderful tuna-fish with olive oil, it is sold in glass containers (look for his fish shop along Cefalu main street, on the right, i f you go towards Palermo). Finally, nobody is allowed to forget about "bottarga": dried tuna-fish eggs which are used to scrape over spaghetti, the same way Parnigiano cheese is used.
Sicilian pastry is great! It has strong influences from the Arabic world and the basic component is almond, or "marzapane": a sweet paste obtained by almonds, sugar, egg yolk and "acqua di zagare", i.e. orange-flowers water. Pistache is also very important, as the area of Bronte (on the North-East slope of Etna volcano) is the only traditional producing area in Italy and the fruits are considered of the top quality.
"Frutta martorana" is fruit-shaped marzapane, painted with vivid colours. "Cassata" is a mixture of marzapane with wheat flour and candies and many more sweets and cakes. "Granita" is a special kind of ice-cream (possibly the mother of ice-cream), made with a sweet syrup with fruits juice or coffe: it is continuosly shaked within a freezing contanier, so that the final result is ice micro-granules with fruit/coffe taste in it. A typical summer preparation is coffee granita, which is a "must" anywhere in Sicily.
Bread is also very good, it is normally baked using durum wheat flour, and sesame seeds are commonly spead on the surface. I had a wonderful experience in a small - but delicious - place in the heart of Madonie, which is called Petralia Soprana. Go to the baker's (Maria Guarnuto - Via Collegio 9 - 0921 641685) and try her bread and her biscuits: they are wonderful!