1 Pour 25cl of water into a saucepan, add the sugar and bring to the boil. Stop cooking
2 Wash, peel the mint (save a few leaves for decoration) and put the rest in the pan. Cover and leave to cool completely.
3 Strain the mint syrup and mix the lime juice and rum together. Pour into a container with a lid and place in the freezer. After 30mn scrape with a fork to obtain a granita. Put back in the freezer and repeat the operation at least 3 times.
4 Cut the pineapple into small pieces. Divide the granita in glasses, decorate with pineapple and reserved mint.