Grow your own ‘elixir of life’. This calorie-free sweetener has been used for centuries in potions believed to treat all manner of ills, from coughs, colds and indigestion to increased sexual vigour. Harvest the two-year-old, pencil-thick lateral roots in the winter. Plant where you can contain the roots as this will make harvesting easier and prevent the plant spreading beyond your herb garden. Roots were sold in the UK during WWI as a `sweet or lolly’.