The ingredients (except for the liqueur and the syrup) should be used well chilled.
Pour the rum, lime juice, peppermint liqueur and elderflower syrup into a 300 ml glass, add ice cubes and fill up with beer. Decorate with mint stalks or leaves.
Variations:
Instead of 2cl rum, 4cl can be used to make the beer cocktail stronger. The other way round, the ingredients can also be filled into a 500 ml glass according to the recipe and poured over with beer, the proportion of high-proof is then lower.