The present document describes a cooking container for cooking foodstuff comprising: an edge having a seal separating the interior from the exterior of the cooking container; a steam valve formed in the seal, the steam valve comprising: a pressure accumulating portion; a pressure controlling portion; and a breakable seal between the pressure accumulating portion and the pressure controlling portion; whereby the breakable seal is breakable under an increase in pressure in the pressure accumulating portion during cooking thereby forming a gap/passage in the seal and permitting controlled evacuation of pressure from the interior of the cooking container through the gap/passage to the exterior, the pressure controlling portion restricting the evacuation of pressure relative to the pressure accumulating portion after the breakable seal is broken.