Place the mascarpone in a bowl and beat with a wooden spoon until softened. Stir in the icing sugar, lime juice and mango purée until well combined. Spoon into the pastry case and spread the top level. Chill for 15 minutes.
Arrange the sliced mango over the top of the tart, cut the passion fruit in half and, holding over the tart, scoop out the seeds and juice and drizzle over the mango. Serve immediately.