Heat the vegetable oil in a large saucepan. Add the onion and ginger and cook for 1 minute on a low heat, then throw in the garlic and chilli. Cook gently for a further 4 minutes, to soften the vegetables. Add the steak, just cover with some stock and simmer with a lid on for 2 minutes for rare, 3 minutes for medium, or 5 minutes for well done. Throw in the noodles and more stock (if it's needed) to cover the noodles. Simmer for 3 minutes. Toss in the peppers and broccoli and cook for another minute. Remove the steak and place on a chopping board. Mix the noodles with the vegetables and serve in individual bowls with the cooking stock. Finely slice the beef and divide between the bowls. Sprinkle over the spring onions, top with a sprig of coriander and serve with soy sauce on the side.
