The invention relates to a system and method for the immersion cooking/cooling of food in diffused forced convection. The inventive system comprises: a tank for housing the food to be cooked/cooled, filling/emptying means for filling the vessel with a cooking or cooling liquid and emptying same, and heating means for heating the liquid. The tank comprises a lower region and an upper region, and circulation means which are intended: (i) to collect liquid from the lower region by means of various outlets in a first lower side wall and to introduce said liquid into the upper region through various inlets in a first upper side wall, and (ii) to collect liquid from the upper region by means of various outlets in a second upper side wall and to introduce said liquid into the lower region through various inlets in a second lower side wall, thereby generating diffused forced convection in a turbulent flow.