a cooking apparatus in a form of a container includes an outer shell and an inner shell wherein a cavity is provided by coupling the edges of the outer and inner shells . the cavity is partially filled with a heat conductive medium , such as silicon oil . the cooking apparatus further includes an electric heating element installed under the container between the outer and inner shells . when energized , the heating element produces heat which in turn heats the silicon oil . the hot silicon oil heats the inner shell and thus cooks the food in the container . the outer shell of the container also has a pressure controlling member that is opened when a cavity pressure exceeds a predetermined value . the pressure controlling member comprises a spring housing securely affixed to the outer shell and defining a first through hole . the spring housing has a valve biased to open when a cavity pressure exceeds a predetermind value . the pressure controlling member also includes a spring disposed in the first through hole to bias the valve in a closed position and a spring suspension member connected to the spring housing to support the spring to bias the valve in the closed position .