Turn off the heat after the pudding surface is set (when you touch the pudding surface with a chopstick you feel a slight bounce it is ready, not ready while the surface is still runny). Cover with a lid completely and leave to stand for 10 minutes to continue to steam with remaining heat. When you put a toothpick in the middle and it stands straight it is done. If not steam for another minute over a low heat and test again. Repeat this until the pudding has set nicely.