Peel the fruit and cut into pieces. Put everything in a saucepan and fill up with 1 liter of water. Add the sugar, vanilla sugar and cinnamon and simmer everything over a medium heat for 45 minutes.
After the cooking time, remove from the stove and let rest for 1 hour, then pour through a sieve, collect the juice and let the fruit drain. You can make jam from the fruit, but it also tastes like that.
Heat the juice again, fill a bottle with hot water and close it, then let it cool down. When the juice has cooled, keep it capped in the refrigerator and use within 4 weeks.