about a quarter of large lime (or half of a medium-sized one)

a small bunch of fresh mint leaves

rum

2 to 3 tablespoons sugar

soda water

ice cubes

Place the lime, mint leaves and sugar in a glass. Muddle them together in a slow but firm circular motion.
Speedy says that the proportion is three parts lime juice to four parts rum. If you don’t get enough juice from your fresh lime, pour in some bottled lime juice (available as a cocktail mixer), then add the necessary amount of rum. Add some ice then pour in enough soda water to fill the glass. And that’s it! Enjoy your cold, cold mojito.