Heat the oven to 425 degrees F. Drain the tomatoes, reserving the juice. Place the tomatoes, onions and garlic into a 17×11-inch roasting pan. Pour the oil over the vegetables and toss to coat. Bake for 25 minutes.
In a large saucepan over medium heat, combine the onions, celery, carrots, garlic and oil and saute for 5 to 10 minutes, or until all vegetables are almost tender. Then add the water, fresh tomatoes, canned tomatoes, chicken broth, barley and ground black pepper.