Abstract: An appliance for cooking under pressure comprises a lid and a bowl having a side wall, said lid and side wall defining an interstitial space presenting an initial cross section of predetermined initial radial dimension for receiving an annular sealing gasket. The bowl, the lid, and the gasket are designed so that when the pressure inside the vessel reaches a predetermined critical value, the interstitial space presents a predetermined critical radial dimension such that the difference between the initial dimension and the critical dimension is great enough to cause leaktight contact between the gasket and the side wall to be broken. The invention is particularly applicable to domestic pressure cookers.