Put the lime wedges, sugar and rum in a shaker or a glass and muddle them well together, ideally with a muddler.
Add the mint leaves and press them lightly with the muddler so they release their oils – just a couple of times. Don't crush them too much.
Add the pulp from both passion fruits and stir well.
Fill 2 glasses with ice, ideally crushed ice, and divide the mixture between the glasses.Don't strain it – tip the lime wedges, mint and all into the glasses too. There is plenty of flavour in them, and it looks lovely and rustic.
Stir well with a spoon so everything is thoroughly mixed with the ice, and top up your passion fruit mojito with soda water.
Garnish with half a passion fruit and a little mint, if you like.