On the next day, add water (7 litres) and calcium carbonate into the cooking pot. Once it is boiling, add the stems, close the pot with a lead and let them cook for 3 hours. You can also use a pressure cooker for this process. If the stems are too stiff, you will need to cook them for a longer period (it will depend what season you harvested the stems). This process is important to soften the fibre.