Cut the watermelon into cubes (remove the seeds if any) and freeze on a tray with parchment paper on it. Make sure the cubes are not touching each other.
Freezer overnight.
Add all the ingredients to a food processor and blitz. It shouldn’t take more than 15-30 secs.The consistency at this point should be like the one in the video, almost like a granita texture.
Transfer the mix into a container and flatten it with a spoon. Now you’ll be able to scoop it up and make balls easily.
If you have any leftover store it in the freezer and take it out for 10-15 mins to defrost slightly before serving.