In a small bowl, combine flour, stock, sugar and soy sauce. Stir until sugar and flour are dissolved.
In a large frying pan or wok over high heat, stir fry steak 2 to 4 minutes, or until browned. Stir in stock mixture, ginger, garlic and broccoli. Bring to the boil, then reduce heat. Simmer 5 to 10 minutes, or until sauce thickens.
I followed other peoples tweaks and doubled the amount of garlic, ginger and stock and added a half tea spoon of chilli. And this sauce was superb. My broccoli was slightly under done and my beef slightly over, but that's something for me to work on. I loved this sauce however.