Put 2–3 teaspoons of brown sugar into a glass and squeeze the juice of two limes into it. Then cut a third lime into small pieces. Add 8–9 fresh mojito mint leaves. Gently muddle the lime, sugar and mint without overdoing it. Pour in 1/3 white rum and 2/3 tonic water. Stir and finish with ice to taste, which is essential for chilling the drink and diluting it.