Peel the mangos, remove the pits and then puree until smooth.
Bring the hot water to a boil; add the gelatin powder and mix well until dissolved and smooth.
Add the sugar and the coconut milk; stir until the sugar is completely dissolved.
Add the mango puree; mix well again.
Pour the pudding mixture into individual shallow bowls or ramekins; chill, in the refrigerator, for at least two hours until set.
Garnish with chopped mango and/or coconut before serving.