Pressure cooking is the process of cooking food at high pressure, employing water or a water-based cooking liquid in a sealed vessel known as a pressure cooker. High pressure limits boiling and permits cooking temperatures well above 100°C (212 °F) to be reached.
The pressure cooker, works by expelling air from the vessel, and trapping the steam produced from the boiling liquid inside. This raises the internal pressures and permits high cooking temperatures. This, together with high thermal heat transfer from the steam, cook food far more quickly, often cooking in between half and a quarter the time for conventional boiling. After cooking the steam is released so that the vessel can be opened safely.
Almost any food that can be cooked in steam or water-based liquids can be cooked in a pressure cooker.