Place the cornflour in a jug and stir in 1 tablespoon of the orange juice. Add the remaining orange juice and sweet chilli sauce and stir to combine.
Heat the oil in a wok or large frying pan and when very hot, add the beef and ginger and stir-fry for 3–4 minutes until browned. Add the spring onions and mangetout and stir-fry for 1 minute.
Add the orange juice mixture and cook, stirring continuously, for 1–2 minutes until the mixture thickens and coats the beef. Serve immediately.