Put the cranberries, sugar and water into a saucepan, bring to a simmer and allow to bubble for 10 mins until the sugar has dissolved and the berries burst.
Leave to cool, allowing the cranberries to steep for a few hours or overnight.
Strain the mixture into a jug, pushing it through the sieve with the back of a spoon, to make a syrup.
To make the mojitos, put 10 mint leaves in each of four glasses and add the juice of half a lime each, then mix and crush with the handle of a wooden spoon.
Add 4 tbsp white rum per glass, 4 tbsp of the syrup, and the ice and stir well or shake together in a cocktail mixer.
Top up with soda water and add a sprig of mint and a few cranberries to serve.
Use white rum for a classic Mojito flavour or spiced rum for a richer Christmassy taste.
Recipe by appetite magazine at https://www.appetitemag.co.uk/cocktail-cranberry-mojito/