1.  2 cups sugar
  2.  1½ cups water
  3.  2 cups fresh lemon juice, strained
  4.  1 tsp grated lemon zest
  5.  3 tsp citric acid
  6.  Soda water or water to serve
  7.  mint leaves

Place the sugar, water, lemon juice and zest in a medium saucepan and heat, stirring, over high heat until the sugar has dissolved.
Bring it to the boil then reduce to a simmer and leave it to bubble away for 20 minutes or until it thickens slightly.
Stir through the citric acid.
Strain the cordial then pour it into a sterilised bottle.
Serve with soda water or water (about 1 part cordial to 4 parts water).
Add fresh mint leaves to decorate.
You can also freeze this recipe up to 6 months.