Heat a wok until smoking hot. Add 1tbsp of the oil and the beef and stir fry for 2 minutes, until browned but still pink. Tip out of the wok into a sieve placed over a bowl. Return the wok to the heat and add the remaining oil and the cabbage and stir fry for 1 minute. Add the garlic, ginger and chilli and cook for a further 1 minute. Add the black bean sauce and beef stock, stir well and simmer for a minute. Return the beef to the pan and heat through. Serve immediately.