Ingredients

Step by step

1. Place the blackberries and lime zest in a medium saucepan with 100ml water and cook over a very low heat for 10-12 minutes, stirring regularly, until the fruit collapses. Strain through a fine-mesh sieve into a jug (see Kitchen Secret), pushing gently to extract all the juice. Transfer the juice to a medium saucepan and add the sugar – you should have about 500ml juice, but if you have significantly more or less, bear in mind that you'll need 350g sugar for every 500ml of juice, so just adjust the quantities accordingly. Discard any seedy pulp left in the sieve (or keep it and sweeten it up with a little honey before stirring through a bowl of yogurt for breakfast).
2. Gently stir the blackberry juice and sugar mixture over a low heat until the sugar has completely dissolved, then increase the heat and bring just to the boil. Once it boils, immediately remove from the heat, then stir in the lime juice and pour the cordial in sterilised bottles.
3. To serve, dilute 1 part cordial with 5 parts chilled water in a jug. Pour over crushed ice with a slice of lime.
   Tip

   If you want your cordial to be clear, instead of sieving, let the fruit drip overnight through a jelly bag or muslin – don't push it through or it will become cloudy.