1 Preheat the oven to 190˚C, gas mark 5. Take the goose out of the fridge 1 hour before cooking to come to room temperature; remove the neck and giblets. Put the oil in a very large roasting tin; heat in the oven until piping hot. Carefully remove the tin and add the goose neck and vegetables; season. Drizzle over the vinegar, then put the goose in the centre, breast-side up.
2 Rub the goose skin generously with the butter and season. Squeeze over the juice from the lemon, then put the lemon in the cavity, along with the thyme and ½ of the rosemary. Chop the remaining rosemary leaves and scatter over.
3 Cover the tin tightly with foil and roast for 3 hours, removing the foil after 2 hours 30 minutes. Every 45 minutes, baste the bird, toss the vegetables and spoon off the excess fat (reserve, if liked).
4 Meanwhile, prepare the stuffing. Heat the butter in a large frying pan until foaming, add the onions and garlic, season and cook over a gentle heat for 15-20 minutes, until soft but not brown. Cool completely, then mix with the remaining ingredients in a bowl until combined. Roll into tight balls, about 2-3cm in diameter.
5 Put the stuffing balls around the uncovered bird and roast for a final 30 minutes, until the thickest part of the goose is piping hot and the juices run clear. Use a meat thermometer to check the goose is cooked. If the thickest part of the bird reaches 75˚C, you’re good to go. Transfer the bird and cooked stuffing to a warm plate or dish, cover loosely with foil and allow to rest for at least 30 minutes before carving.
6 For the gravy, pour off (and reserve) the excess fat from the tin. Put the tin on the hob over a high heat, add the shallot, garlic and giblets, if liked. Sprinkle the flour over the tin and stir for 1-2 minutes. Add the wine or port and simmer vigorously to reduce by half, then pour in the chicken stock. Strain everything through a sieve into a clean saucepan (discard the solids) and simmer vigorously until syrupy. Season and serve with the carved goose and stuffing.