1. In a large glass or stainless-steel bowl, combine the chopped tomatoes with the mozzarella, basil, olives, balsamic vinegar, salt, and pepper.
2. In a large pot of boiling, salted water, cook the spaghetti until just done, about 12 minutes. Drain, add to the tomato mixture, and toss.
3. Heat the oil in a small frying pan over moderately low heat. Add the garlic and cook, stirring, for 1 minute. Pour the oil over the pasta and toss again.
Variations: Add some drained capers, chopped red onion, or grated Parmesan to the pasta.
Wine Recommendation: Valpolicella, the crisp, fruity, cherry-scented wine from the shores of Lake Garda in the Veneto, is the perfect hot-weather wine for tomato-and-herb-based dishes. Try one here for a delightful accompaniment.