Abstract: A cooking vessel is provided with a whistle knob which has an internal passage for carrying steam from a hole in the cooking vessel to a rotary whistle chamber molded in the knob. The whistle chamber is displaced from and eccentric to the knob axis. The lower surface of the knob has a cavity which surrounds the knob axis, providing a steam passage inlet which is in communication with the hole in the cooking vessel regardless of the angular position of the knob relative to its axis. From the inlet cavity, steam passes through a vertically extending passage, a plenum chamber and a horizontally extending passage which introduces steam into the whistle chamber at an angle which causes an audible whistle and rotary movement of the steam. The whistle chamber has an outlet which may be opened and closed by rotational movement of a valve ring which extends circumferentially around the knob.