Rub the sugar and chillies into the fillet and place in a snugly-fitting, non-metallic dish. After an hour, turn the fillet once. Pour the soy sauce over the meat, cover the dish with clingfilm and place in the fridge. Turn the meat by a half rotation every 12 hours for 2 days.
Remove the meat from the marinade and wipe dry with a cloth, then cut it into 4 equal sized steaks, brush with the groundnut oil and leave to sit at room temperature.
Cook the egg noodles following instructions on the packet, then drain. Refresh under cold water and drain again. Cook the meat over a moderate to high heat for 2½ – 3 minutes on each side in a frying pan.