Add the beef, stock, seasoning, and chopped onion to the slow cooker.
Cover and cook on low for about 8 hours or high for about 4.
Cook rice and prepare broccoli.
About 10-15 minutes before serving, transfer to a large stock pot and bring to a boil, uncovered. Stir through the gravy powder and cornflour to thicken.
Microwave the broccoli.
Serve the beef / gravy over the rice, with a scattering of fresh parsley.