300 gmrockmelon, cut into thin wedges300 gmhoneydew melon, cut into thin wedges300 gmseedless watermelon, cut into thin wedges¼ cup(loosely packed) mintTo serve:vanilla or natural frozen yoghurt, and lime wedgesLime-vanilla caramel220 gm(1 cup) caster sugar50 mllime juice1vanilla bean, split and seeds scraped
For lime-vanilla caramel, stir sugar and 60ml water in a saucepan over medium-high heat until sugar dissolves, brush down sides of pan with a wet pastry brush then cook, swirling pan occasionally once mixture starts to caramelise, until dark caramel (4-5 minutes). Remove from heat, place saucepan in sink and carefully add 70ml cold water (caramel will spit, so stand back). Swirl to combine, then add lime juice and vanilla, and swirl again. Transfer to a heatproof bowl and refrigerate to cool.
Combine melon in serving bowls, scatter with mint, drizzle with a little lime-vanilla caramel, top with scoops of frozen yoghurt, drizzle with more lime-vanilla caramel and serve.