How to Make It
In a small enameled cast-iron casserole, heat the olive oil. Season the meat with salt and pepper and add to the casserole. Cook over moderately high heat until browned on 2 sides, about 3 minutes per side. Add the carrots and onions and cook over low heat, stirring occasionally, until softened, about 10 minutes. Sprinkle the flour over the meat and vegetables and stir until dissolved. Add the red wine and water and bring to a simmer over moderately high heat, stirring occasionally. Cover and simmer over low heat, turning the meat once or twice, until very tender, about 2 hours.
Meanwhile, In a large saucepan, cover the potatoes and celery root with water and bring to a boil. Simmer over moderately high heat until tender, about 20 minutes. Drain the potatoes and celery root. Return them to the saucepan and shake over moderately high heat to dry them out, about 1 minute.
Using a potato masher, mash the potatoes and celery root until creamy. Gradually mash in the milk. Stir in the butter and season with salt and pepper.
Preheat the oven to 400°. Remove the meat from the casserole and coarsely shred it with 2 forks. Alternatively, coarsely chop the meat. Boil the juices in the casserole until nicely thickened, about 8 minutes. Return the shredded meat to the casserole and season with salt and pepper.
Spoon the stew into a 9-inch square baking dish. Spread the mashed potatoes and celery root over the stew and sprinkle with the bread crumbs. Bake for about 15 minutes, until the stew is bubbling, the topping is hot and the crumbs are crisp. Let stand for 10 minutes before serving.