Soak the chufa nuts in water for 24 hours.
In a blender, grind the nuts, water, cinnamon, sugar and lemon until you have an even, smooth mixture.
Let it settle for a half an hour.
Press the paste through a strainer to obtain fresh horchata.
Refrigerate for at least an hour.
Finish in the freezer for 20 minutes until slightly slushy.