Add the rice and milk to a saucepan on a low heat. Cut the vanilla pod in two and scoop out the seeds, adding them and the pod to the saucepan. Cook for around 20 minutes, stirring occasionally until the rice is tender and creamy.
Once cooked, stir in the sweetener and the juice and zest of the lime.
Serve immediately topped with one half of the scooped out passion fruit on top, and one half to garnish.