1. Cook the tongue, jointly with the celery, the carrot, the laurel leaf and the salt in a stew with a lot of water, during one hour approximately. Take out the tongue and let it cool down.
2. Prepare the pickle: put mustard, lemon juice, vinegar and olive oil in a bowl. Mix with a fork. Cool down in the fridge for some hours. Peel the tongue and put it in the pickle bowl. Let it stand in the fridge during some hours.
3. Take the tongue out of the pickle and cut it in thin slices. Place it in a platter, like Carpaccio and reserve.
4. Cut into pieces the peppers, spring onions and gherkins. Add them into the pickle with the capers.
5. Add salt and pepper and mix well. Put the greens and the pickle over the tongue. Serve this course cold.