Preheat the oven to 180°C (fan-forced). Mix the olive oil with BBQ Bloke Spice and rub the marinade all over the beef. Place the meat in a deep roasting tray, sprinkle with a couple of pinches of salt and pour about 1/4 cup of water over the base of the tray. This will keep the meat moist while it cooks. Cover the tray with a double layer of aluminium foil, seal tightly and place it in the oven.
While the brisket cooks, make the BBQ sauce. Place all the ingredients in a small pan over a low-medium heat for 10 minutes, stirring occasionally until thickened. Set aside.
After an hour, baste the brisket with the juices that have dripped on the baking tray, cover with the foil again and put it back in the oven. Repeat the process every hour until the meat is tender. The cooking time will depend on the size of the brisket - it takes about 2 hours per kilo of meat.
To make the coleslaw, finely slice the cabbage and put it in a bowl. Cut the apples into matchsticks and place them in the same bowl. Add the salt and massage it in slightly for a few seconds, then add the yoghurt, lemon juice, mustard and chives and mix well. Cover and refrigerate until the brisket is ready.
When the brisket is tender (around the 3.5 hour mark, if using a 2kg brisket), take the aluminium foil off and brush a generous layer of BBQ sauce over all its sides - using a spoon is best for this. Put it back in the oven for a further 20–30 minutes until it’s caramelised. Lower the oven’s temperature if the BBQ sauce starts to burn.
Take the brisket out of the oven, cover it with foil again so it doesn’t dry out and let it rest for about 20 minutes. Serve with the BBQ sauce and coleslaw.