Place the corn in a large pot with enough water to cover, and bring to a boil. Cook 5 minutes, until kernels are tender but crisp. Drain, cool slightly, and use a knife to scrape kernels from the cobs.
In a large bowl, mix the corn kernels, red bell pepper, onion, tomato, olive oil, balsamic vinegar, and garlic. Season with pepper. Chill 15 minutes before serving.