Heat oven to 325 degrees. Rub the garlic, cut sides down, over surface of beef brisket; reserve garlic. Heat the oil in a skillet over medium heat. Place brisket in the skillet; cook, turning once to brown evenly. Remove brisket from skillet; season with salt and pepper. Pour off drippings. Place onions and reserved garlic in the bottom of a large, deep baking pan; place brisket over onions. Stir in the wine, tomatoes with their juice, celery, rosemary, thyme, and bay leaf. Cover; bake, basting frequently with cooking liquid, 3 hours. Add the carrots and parsley to cooking liquid. Uncover; continue cooking until brisket and carrots are tender, about 30 minutes. Remove brisket; keep warm. Skim fat from the cooking liquid; discard the garlic and bay leaf. Cut diagonally across grain into thin slices. Serve with the cooking liquid.