A method for cooking food includes heating a liquid cooking medium in a cooking vessel having a nullUnull-shaped structure having a height is sufficient, with sufficient medium added, to attain a hydrostatic pressure at a predetermined lower depth that is substantially greater than ambient atmospheric pressure. The food is conveyed through the vessel, mostly cooking at the bottom, where the hydrostatic pressure facilitates a cooking of the food at a rate substantially greater than a rate at ambient pressure. A further aspect of the invention is a method for reducing wastewater output and makeup water usage when cooking a food containing a complex carbohydrate. This method causes released complex carbohydrate to cause a lower viscosity increase than at ambient pressure, thereby increasing a cooking effectiveness of the water and reducing a need for adding makeup water and disposing of wastewater.