Score the fillet 3 cm deep along its full length. Season the inside with salt and pepper, push a few plums and 2 thyme sprigs into the incision. Then close the lung roast and tie with spaghetti.
Cut pumpkin flesh into large cubes, peel and finely chop onion, unpeeled garlic cloves once heartily smooth.
Melt butter in a roasting pan. Sauté fillet on all sides in the foaming butter until golden. Add garlic, thyme, onion and remaining plums as well as the pumpkin cubes, drizzle everything together with honey and caramelize. Then deglaze with sherry. Season with salt and pepper – simmer on a gentle heat for 35 minutes with the lid closed. Then lift the fillet out of the stock, drain briefly over it, then cut into thick pieces. Season the stock and bring to the table with the fillet very hot.