Cut tomatoes in half lengthwise; place, skin side down, in a lightly greased 15- x 10-inch jellyroll pan. Sprinkle with 1/2 teaspoon pepper.
Bake at 300° for 1 to 1 1/2 hours or until tender and lightly charred; cool. Cut into 1/4-inch pieces; set aside.
Cut potatoes and next 3 ingredients into 1/2-inch pieces; drizzle with 2 tablespoons olive oil, tossing gently. Place in a jellyroll pan.
Bake at 400°, stirring occasionally, 30 minutes or until tender. Set aside.
Cube chicken; chop celery and onion. Sprinkle chicken with 1 teaspoon pepper; sauté in remaining 1 tablespoon oil in a large Dutch oven 5 minutes. Add celery, onion, and garlic, and sauté 2 to 3 minutes. Add broth; cook over medium heat, stirring occasionally, until vegetables are tender.
Add roasted vegetables, tomato paste, salt, and remaining 1/2 teaspoon pepper; cook, stirring often, until thoroughly heated. Stir in parsley and rosemary.