Place the fresh mint leaves and a lime wedge into a sturdy glass or tumbler.
1 bunch fresh mint leaves, 1 lime lime wedge
Use a muddler to gently press and twist the mint and lime to release their aromatic oils and juices, until the mint leaves appear bruised and fragrant.
1 bunch fresh mint leaves, 1 lime lime wedge
Add the elderflower syrup to the glass, stirring slightly to combine with the muddled herbs and lime.
1 oz elderflower syrup
Fill the glass with ice cubes, then pour the chilled Prosecco over the mixture, filling about three-quarters of the glass.
3 oz Prosecco
Top off with a splash of sparkling water or soda if desired, then gently stir to combine all ingredients without losing carbonation.
Splash sparkling water or soda
Garnish with additional mint leaves and a lime slice on the rim of the glass before serving.
1 bunch fresh mint leaves, 1 lime lime wedge