Heat a little of the oil in a large flameproof dish. Add the beef chunks, in batches, and fry until browned. When each batch is browned, transfer the beef to another dish. Very roughly chop the onions, ginger, garlic and coriander stalks. Put in a food processor and whizz to a paste.
Wipe any oil out of the dish you browned the beef in. Add the paste with a good splash of water and gently fry, scraping up any beef bits, until the paste is fragrant and softened (add more water if the paste sticks). Stir in the five-spice, star anise and peppercorns, cook for 1 min, then add the sugar, soy sauces and tomato purée. Return the beef and any juices to the dish, then stir in enough stock to just about cover. Bring to a gentle simmer. Heat oven to 160C/140C fan/gas 3. Cover the dish, put in the oven and cook for 21⁄2 hrs until the beef is really tender.
Lift the beef out of the sauce into a dish, to keep warm. Boil the sauce until reduced by about half and thickened. Meanwhile, fry the ginger in the oil until golden and crispy. Return the beef to the sauce. serve the beef spooned over rice and scattered with the crispy ginger.
