To make the beef mince, heat the vegetable oil in a heavy-based saucepan over a high heat for 1–2 minutes. Add the garlic and ginger and fry for 30 seconds. Add the onion and celery and fry for 2–3 minutes. Add the beef mince and use a wooden spoon to break it up into small pieces. Cook for 6–8 minutes, or until the liquid has evaporated and the meat is browned. Add the stock, doubanjiang, soy sauces, oyster sauce, sugar and MSG. Bring to the boil, then reduce the heat to low.