Dip a measuring cup into the cooking liquid, add about 125ml/4fl oz and mash using your chosen method (see recipe tip). You may want to add more of the cooking liquid. I never add less than 250ml ...

Remove the lid, increase the heat and boil hard for a further 5 minutes, or until the swede is soft and the liquid has reduced to around 5 tbsp. Remove the pan from the heat and mash until smooth.