Combine tomatoes, sun-dried tomatoes, garlic, olive oil, vinegar, basil, salt and pepper in a large bowl. Allow the mixture to sit for 10 minutes at room temperature.
Meanwhile, cut the baguette into 3/4-inches slices.
Arrange the baguette slices in a single layer on the Large Cookie Sheet. Broil for 1 to 2 minutes, until slightly brown.
Divide tomato mixture evenly over the baguette slices. Top the slices with mozzarella cheese.
Broil for 5 minutes, or until the cheese is melted.