The Porto sauce: chop shallots, red onion, chestnut mushrooms and garlic cloves in brunoise. Keep a few nice big mushrooms. Stew the chopped vegetables in some butter. Add thyme, bay leaf, ginger, cloves, juniper berries, star anise, tarragon, a few turns of the pepper mill and peeled tomatoes and simmer for another five minutes. Then add red wine, Port wine, veal stock and balsamic vinegar and reduce by 1/3. Sieve the sauce and thicken if required. The vegetables: cut the preserved mushrooms into slices and fry them over a high heat in a pan sprayed with a little olive oil. Cut cylinders out of sweet potato and yellow turnip. Steam them for a few minutes, let them cool down and then fry them brown in a pan with a little butter.