Cook the broccoli in a steamer for 3 minutes or until crisp-tender; put aside. Combine the soya sauce and sherry in a medium bowl. Add the chicken and toss.
Heat the oil in a large nonstick frying pan. Add the chicken and stir-fry for 3 minutes; transfer to a plate. Add the ginger and garlic and stir-fry for 30 seconds. Add the broccoli and capsicum and stir-fry for 2 minutes.
Add the stock and chilli sauce and bring to the boil. Combine the cornflour with 1 tablespoon water; add to the pan and stir for 1 minute or until slightly thickened. Return the chicken to the pan; add the spring onions and cook for 1 minute. Stir in the cashews just before serving.