Place beef in the slow-cooker. Arrange potato, carrot, onion, bay leaves and thyme around beef. Season with salt and pepper.
Combine passata (or can of tomatoes), garlic, stock and 1 cup cold water in a jug. Pour over beef. Cover with lid.
Turn cooker to low. Cook for 8 hours or until vegetables are tender, turning beef halfway during cooking.
Transfer beef to a plate. Cover loosely with foil. Set aside for 10 minutes. Slice thinly. ServeĀ