Line a 13x9x2-inch baking pan with foil. Remove and discard stems from tomatoes; wash tomatoes. Pat tomatoes dry with paper towels. Arrange tomatoes in a single layer in prepared pan. In a small bowl whisk together oil, vinegar, garlic, salt and pepper. Pour over tomatoes and toss tomatoes to coat.
Bake, uncovered, in a 400 degree F oven 14 to 18 minutes or just until the tomatoes are soft and skins begin to split, gently stirring once.
Transfer the tomatoes to a shallow serving bowl. Drizzle the balsamic mixture from the pan over the tomatoes. Sprinkle with snipped basil. Serve warm or at room temperature. If you like, garnish with fresh basil sprigs and serve with bread to dip in the vinegar mixture. Makes 8 side-dish servings.
For a richer flavor, heat 1/3 cup balsamic vinegar in a small saucepan over medium heat until boiling. Boil gently, uncovered, for 6 to 8 minutes or until reduced to 2 tablespoons, watching carefully at the end because vinegar will reduce quickly.