Combine flour, salt and pepper; dredge meat. In a large skillet, heat the oil on high. Brown meat on all sides. Lay the shanks flat in a Dutch oven or oblong baking dish and sprinkle with Italian seasoning and sage. Combine onion, garlic, carrots and celery. Sprinkle over meat. In a small bowl, whisk together wine, broth and tomato paste. Pour over vegetables. Cover and bake at 325 for 2 hours or until fork-tender. Just before serving, combine Gremolata ingredients; sprinkle over each shank. Serve immediately. Yields 4-6 servings.