Toss the short ribs in a large bowl with s&p to coat. Heat the oil in a Dutch oven over high heat until smoking. Add the beef and cook, without moving it, until well browned on first side, about 5 mins. Stir the beef and continue cooking, stir occasionally, until browned all over, about 10 mins total. Reduce the heat if the bottom of the pot begins to scorch. Return the meat to the bowl and set aside.
Return the pot to medium-high heat and add the carrots, celery, and onion. Cook, stirring frequently, until the vegetable begins to brown, about 4 mins. Add the vegemite, soy sauce, garlic, and tomato paste and cook, stirring, until fragrant, about 30 seconds.
Add the stock and scrape up the browned bits from the bottom fo the pot with a wooden spoon. Add the tomato, barley, and bay leaves, then return the beef to the pot, increase the beef to high, and bring to a boil. Reduce to the lowest possible hear and cover the pot, leave the lid slightly ajar. Cook, stirring occasionally, until the beef is completely tender and the barley is cooked through, about 2 hours.
Stir in the kale and cook, stirring constantly, until wilted, about 2 mins. Season to taste with s&p. Serve, or for the best flavour, cool and refrigerate in a sealed container for up to 5 days before reheating and serving.