First "dry shake" all the ingredients (meaning everything except the ice cubes and mineral water) thoroughly.
Then add ice cubes and mix again briefly. Finally add the mineral water. For the foam : Either beat 1 egg white with a hand mixer until frothy. To make a vegan drink use aquafaba (chickpea water) instead of egg white. Whip up the aquafaba with the hand mixer and you get a similar, often even nicer foam than with an egg white.
Add the foam on the drink and decorate with rose petals as desired.