Photo: Karen Thomas
Put the lime juice, the lime shells, the passion fruit pulp, the pieces of lemongrass and about a third of the mint in a jug. ‘Muddle’ all the ingredients together with the end of a rolling pin, stir in the gomme and rum. Set aside for an hour or so if time allows.
Strain the cocktail mix through a sieve, pushing with the back of a spoon to make sure you get as much pulp and flavour as possible; discard the lime shells, lemongrass, mint and passion fruit seeds.
Put some ice and mint leaves in each of 8 highball glasses, fill each one a third full with the cocktail mix and top up with equal amounts of soda water and ginger ale.
Add a lime wedge to each glass and half a passion fruit if you are feeling fancy.