Preheat your oven to 200°C (400°F, gas 6).
Place the pork shoulder in a snug-fitting roasting tray.
Drizzle the pork shoulder with olive oil and red wine vinegar.
Grate the whole nutmeg over the pork, and season generously with sea salt and black pepper.
Rub the seasoning and oil mixture all over the pork shoulder.
Peel and halve the red onions, then add them to the roasting tray.
Place the roasting tray in the oven and immediately reduce the temperature to 150°C (300°F).
Cook the pork for about 4-5 hours, or until the meat is tender and pulls apart easily with a fork.
Remove the pork from the oven and let it rest for about 30 minutes before shredding.