Remove any butcher's string from your brisket, unroll and season all over with salt and pepper.
Using the sear function on your multi-cooker, add 1 tbsp of the sunflower oil and sear your brisket until it's browned all over.
Remove the meat and set aside on a plate. Add the remaining oil and cook the onions for around 5 minutes until softened.
Add your powdered ingredients to the pan and stir to cover the onions.
Stir in the sugar and add the vinegar, allowing it to bubble for a couple of minutes before adding the ketchup followed by the beef stock.
Return the beef to the pan and set to slow cook for up to 6 hours. After 4 hours, check on the meat periodically until it's falling apart.
When the meat is ready, remove it from the pan. Set the multi-cooker to sear and reduce the cooking liquid until you have a sauce-like consistency. Whilst the sauce is boiling, pull the brisket apart with a set of tongs or two forks in a bowl.
When the liquid is reduced, return the meat to the pan and mix to cover it in the sticky barbecue sauce.
Serve in soft rolls with seasoned wedges, coleslaw and corn on the cob.