Heat the oil in a large shallow saucepan or flameproof casserole dish. When it’s shimmering, add the wings and the turkey pieces, and spend a good 20 mins browning them well in the oil – sticky bits of meat in the pan will add flavour.
Tip in the vegetables, herbs and porcini, scatter over the sugar and stir everything in. Turn down the heat and brown the vegetables for another 10 mins. Stir in the flour, then pour in the Prosecco and simmer down to a paste.
Stir in the stock and bring to the boil, scraping the bottom of the pan as you stir. Skim any scum off with a ladle and simmer steadily for 30 mins until thickened and reduced by about a third. Season to taste with salt and stir in a squeeze of lemon. Leave to cool slightly, then strain through a sieve into a container and chill. Can be made three days ahead, or frozen for up to three months.
On the day, simply reheat or pour into the turkey roasting tin and reheat with the roasting juices. If not serving to children, finish with a splash more Prosecco just before serving, if you like.