Fresh mozzarella is generally considered a seasonal food. Demand goes up with the arrival of fresh tomatoes in the garden and in the farmers' markets and then crashes again in early fall.
I buy it year-round though. In fall and winter I replace those fresh tomatoes with cooked vegetables. Three of my favorites combinations are fresh mozzarella...
... with sauteed peppers and onions. This combination I discovered as a vegetarian. I had a craving for a peppers and sausage sandwhich one day. I replaced the sausage with fresh mozzarella, and added lots of oregano to the peppers and onions. Delicious.
... with artichoke hearts. This is a new one. I saute a little onion in a melted cube of basil frozen in olive oil, and then add sliced artichoke hearts (preferably frozen, not canned) and a splash of red wine vinegar.
... with sauteed mushrooms. I saute garlic with fresh mushrooms and herbs. I prefer oregano with the woodsy flavor of mushrooms, but anything you like will do.
These sandwhiches are perfect for other odds and ends as well. A few sliced olives, a few slices of roasted peppers from a jar, whatever you have on hand. So, the next time you see those fresh mozzarella balls on sale in the grocery store, go ahead and buy a few, even if tomatoes are not in season.