Rub the beef with the sugar and chillies. Place in a non corrosive dish and pour over the soy sauce. Cover with cling film and marinade in the fridge overnight, turning a few times.
Remove the meat from the marinade (reserve the marinade) and wipe dry with kitchen roll. Cut into 4 equal size steaks and brush with peanut oil.
Heat a heavy griddle pan.
Meanwhile cook the noodles, refresh under cold water and drain again.
Place the steaks on the griddle and cook for 2-3 mins each side.
While beef is cooking, heat a wok and add 2 tbsp peanut oil. Add the beans and toss lightly to give a little colour. Add the noodles and toss. Then add the reserved marinade, coriander and sesame oil. Heat through. Sprinkle on the spring onions at the last minute.
Divide the noodles among 4 plates and place a piece of beef on each one.