Season the beef well with salt and pepper.
Heat the olive oil in a heavy casserole dish over high heat and sear the meat until very well browned on all sides then set aside.
Add the diced carrot,celery,onion,garlic and capsicum,reduce the heat to medium and fry for about 10 minutes,stirring frequently. Add the paprika,flour and Vegemite (if using) and fry for a further 2-3 minutes.
Add the soy sauce,tomatoes,stock and herbs and return the beef to the pot. Cover and simmer for about 2½ hours,stirring occasionally until the beef is tender.
Place the chocolate in a small saucepan with half a cup of the liquid from the goulash. Stir frequently over medium heat until the chocolate is melted and combined with the liquid.
Stir the chocolate sauce through the goulash,and then add the remaining chunky carrots and quartered potatoes. Simmer uncovered for 30-45 minutes until the carrot and potatoes are soft and the goulash is thick and dark. Sprinkle with parsley and serve.
Adam's tip: Cutting meat into"bitesized pieces"is often a mistake. Meat will shrink during cooking so it can end up as firm nuggets or sloppy mush. It's much better to leave meat in bigger chunks for long braises. They'll have a better texture while still being soft enough to tear apart.