Cut brisket in half or roll to fit into crockpot. Add chopped onion, chopped carrot, bay leaf, thyme, salt and water. Cover and cook on low 8 to 10 hours. When meat is done, lift gently from stock. Support underneath with a spatula and keep warm. Add small onions and carrots to stock in crockpot. Cover and cook on high 1 to 2 hours. Remove vegetables from broth with a slotted spoon and arrange around the meat.