Potato-Yoghurt Purée

• 200 g (7 oz) desiree potato, unpeeled
• 75 g (2¾

Place the potato in a saucepan of cold water, bring to the boil and cook until tender. Drain and remove the skin. Pass through a food mill (mouli or ricer) or drum sieve (tamis). Fold in the butter and arrowroot, then whisk in the yoghurt until smooth. Set aside and keep warm.