Heat the Wilson's Rosemary Flavoured Oil in the potjie pot over hot coals or on the stove. Brown the beef shin in batches until deeply coloured on all sides, then set aside.
Add the onions, garlic, carrots and celery to the same pot and cook for a few minutes until they start to soften, stirring up any browned bits from the bottom.
Sprinkle the flour over the vegetables and stir through to coat everything evenly.
Return the beef shin to the pot. Pour in the beef stock and red wine, then add the bay leaves and rosemary sprigs.
Bring to a gentle simmer, cover with the lid, and cook low and slow for about 3 hours, checking occasionally to make sure it isn't catching at the bottom.
Add the potatoes to the pot in the last 45 minutes of cooking and season with salt and pepper to taste.
While the potatoes cook, make the dumpling. Combine the self-raising flour and salt in a bowl, then rub in the cold butter until the mixture looks like coarse crumbs.
Stir in the milk a little at a time until you have a soft, slightly sticky dough. Fold through the chopped parsley if using.
Shape the dough into one large ball, or several smaller ones, and place on top of the simmering potjie.
Cover and cook for a further 20 to 25 minutes without lifting the lid, until the dumpling has puffed up and cooked through.
Serve straight from the pot, spooning the beef, vegetables and gravy over each portion of dumpling.