To make the mango jellies, puree the mango in a blender with the lime juice, then pour the mixture into a measuring container -- you will need 250 ml (1 cup) liquid. If you don't have quite enough, top up with water or orange juice. Set aside.
Put the sugar and orange juice in a small saucepan over medium heat. Stir until the sugar has dissolved, then pour the liquid into a bowl. Sprinkle the gelatine over the warm liquid and stir for a minute or two to ensure that it is evenly dissolved. Stir in the mango puree mix, then ladle into four 150 ml jelly moulds or ramekins. Cover with plastic wrap and refrigerate overnight.
Just before serving, put the pineapple, peach, passionfruit pulp and orange juice in a bowl and gently mix together.
Dip the moulds in hot water, then turn the jellies out onto four dessert plates. Spoon the fruit salad around them.