Rinse the sweetbread thoroughly and in the meantime heat up the barbecue using the aromatic wood. Place the coals on top and allow them to burn. Let the burned coals cool down and then crush them into a powder. Bring the water to a boil with the aromatics and poach the sweetbread. Carefully peel the sweetbread and let it cool down. Vacuum pack the sweetbread with the ground charcoal and let it infuse for 1 night.
Season the sweetbread with salt and pepper and roast it until crunchy on the barbecue with some clarified butter. Wash and peel the salsify and steam sous vide for 17 minutes.
Thinly slice the salsify and pickle it. Roast the pattypan squash at the edge of the barbecue. Wrap the celeriac in aluminium foil and cook in between the wood blocks. Cut it into slices, cut out rounds, and season with salt, pepper, and clarified butter.
Roast the chestnuts on the open fire, pare them, and mix them with the cream until smooth. For the gravy, make a caramel of the sugar, shallots, and garlic. Deglaze with vinegar and reduce until smooth. Add the calvados, reduce until half, add the veal fond and ginger, allow it to infuse for 2 hours. Pass the gravy through a sieve. Shingle the marinated salsify slices on a plate and plate up the sweetbread.
Garnish with the remaining components and drizzle the last bit of gravy on top.