I too will be in SIracusa Sicily over Christmas. Any good markets in the area?
Ortygia has a colourful daily morning open air market for fruit, vegetables, meat and fish. Turn left as you approach Ortygia from Siracusa.
http://www.bestofsicily.com/mag/art85.htm
Ditto to what Giovanna said, there is a large car lot very close to where the market is so no need to worry about parking if you're not staying on Ortygia. Also, check out Castello Fiorentino for the best pizza in the area (dare I say, all of Sicily?). The "bella donna" pizza is my favorite, I could sure go for one right now