Peel the carrots and onions and then slice them thinly. Immerse the tongue in a saucepan filled with water, bring to the boil and cook for another 5 minutes. Rinse the meat, repeat the process, this time adding the carrots, onions, bouquet garni and celery. Cook for 3 hours, or until the meat is very tender.
Once the tongue is cooked, remove the skin, then thin