Place ice cubes, chopped watermelon, honey, lime juice and salt into the blender bowl. Blend everything on low speed for around 40 seconds.
Now add the mint and blend another 10 seconds. Check the consistency. If as desired, pour into glasses, decorate with some more mint and enjoy!
Notes
Why adding salt? Salt lowers the melting temperature of ice. Adding a pinch of salt helps to keep the slushy cold for a longer time. Don't worry: you won't taste the salt.