Slit open the vanilla stick, puree the blueberries and bring to the boil together with the ingredients except the sugar and simmer for about 20 minutes.
Add the sugar and stir, it should continue to simmer until the sugar has dissolved.
Put everything through a sieve, bring to the boil again and fill into well-sealable bottles while still hot and let them cool down.
Use: As a lemonade with sparkling water or mineral water in a ratio of 10: 1 or you can try it yourself how it tastes.