Season brisket with salt and pepper. In a Dutch oven, brown brisket in oil over medium-high heat. Remove and keep warm. In the same pan, saute onions and garlic until tender. Place brisket over onions. Add the wine or broth, tomatoes, celery, thyme, rosemary and bay leaf.
Cover and bake at 325° for 2 hours, basting occasionally. Add carrots; bake 1 hour longer or until meat is tender. Discard bay leaf. Cool for 1 hour; cover and refrigerate overnight.
Trim visible fat from brisket and skim fat from tomato mixture. Thinly slice beef across the grain. In a saucepan, warm tomato mixture; transfer to a shallow roasting pan. Top with sliced beef. Cover and bake at 325° for 30 minutes or until heated through. Serve sauce over beef. Yield: 12 servings.