To make your homemade soda, combine in a siphon: The peel of a grapefruit, 1 rosemary sprig, 500ml of water.
Add 2 chargers of CO2 to make it fizzy
Combine all ingredient in a highball full of ice
Organise your soirée
Put the quantity of ingredients you have, to know how much other ingredients you need and how many cocktails you can make.