Directions

1. First, use a serrated knife to cut around the flesh of your watermelon halves. Use an ice cream scoop or large spoon to remove all the flesh, including the pips, into a large bowl. Transfer to a blender or food processor and blitz until smooth.
2. Strain the pulp through a fine sieve into a large bowl to extract all the juice. You should be left with about 800ml of watermelon juice. Meanwhile, put the watermelon halves in a medium roasting tin lined with kitchen paper. Make sure the watermelon fits in snugly so it's easily transferable to the fridge.
3. Pour 50ml of the juice into a small saucepan and bring to the boil. Once boiling, add the sugar and leave to dissolve for 2 mins. Once cooled a little, squeeze out the soaked gelatine leaves and stir through the warm watermelon juice to dissolve. Once fully dissolved, combine with the rest of the watermelon juice and add the vodka.
4. Ladle equal amounts of the juice into each watermelon half. Transfer to the fridge to set for at least 4 hours, preferably overnight. When ready to serve, use a serrated knife to cut the watermelon into about 15 wedges. Serve with a warning: these contain lots of vodka!