Furthermore, if you boil an egg for 20 to 25 minutes at between 70 to 75 degrees, you can make an onsen egg without the necessity for a container, however it is necessary to have a way of maintaining the boiling and temperature.
また、20～25分間70～75度に湯の温度を保って卵を茹でれば温泉卵はでき、容器に拘る必要はないが沸騰や温度の降下に至らないように工夫する要領が要る。