Wash the strawberries, cut a few into small pieces and puree the rest with sugar and lemon juice (if you like, you can puree a few leaves of basil with it). Pour cold mineral water on the syrup. Pour the pureed strawberries with the elderflower lemonade.
Serve in glasses with ice cubes, fresh basil and strawberry pieces.
Tip: If you want, you can add a few lemon zest to the drinks.