Cut the beef thinly across the grain and place into a bowl. Add the ginger, garlic and chilli. Spray lightly with oil to coat the beef then stir to combine.
Heat wok over high heat until hot. Add sesame seeds and stir-fry for 1 minute until golden, remove to a plate. Spray the hot wok lightly with oil then add one-third of the beef and stir-fry for 1-2 minutes until sealed, remove beef to a plate. Repeat in two batches using remaining beef.
Spray wok lightly with oil and add the bok choy stems, carrot, capsicum and beans and stir-fry for 1 minute. Return all the beef and any juices on the plate. Combine the soy and sweet chilli and pour over the beef, stir-fry for 1 minute. Add the bok choy leaves, beans sprouts and sesame seeds, stir to combine. Remove from the heat and serve with rice.