1. In a small bowl, combine flour, stock, sugar and soy sauce. Stir until sugar and flour are dissolved.
2. In a large frying pan or wok over high heat, cook and stir steak 2 to 4 minutes, or until browned. Stir in stock mixture, ginger, garlic and broccoli. Bring to a boil, then reduce heat. Simmer 5 to 10 minutes, or until sauce thickens.