Cut tomatoes in half lengthwise; place tomato halves, cut side down, in a 15- x 10- x 1-inch jellyroll pan coated with cooking spray. Coat each tomato half with cooking spray; sprinkle evenly with Italian seasoning, pepper, and garlic. Bake at 500° for 15 to 20 minutes or until tomato skins are charred. Let cool slightly. Position knife blade in food processor bowl; add tomato. Process 3 or 4 times or until slightly chunky.
Coat a medium saucepan with cooking spray; place over medium-high heat until hot. Add onion; saute until tender. Stir in tomato mixture, vin-egar, salt, and beef broth. Bring to a boil; reduce heat and simmer 5 minutes.
To serve, ladle soup into individual bowls, and top evenly with cheese.