How to Make It
In a large glass or stainless-steel bowl, combine the chopped tomatoes with the mozzarella, basil, olives, balsamic vinegar, salt, and pepper.
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.
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.