Cut the melon with a long knife all around in a jagged shape up to the middle. Carefully take the halves apart. Remove seeds with a spoon. Carefully cut the flesh from the skin and divide into small triangles.
Keep the halves of the bowl. Peel mangos and cut the flesh in small pieces from the stone. Drain the water chestnuts on a sieve. Wash lime hot, dab dry. Peel the skin thinly, cut into fine strips and put aside.
Squeeze the juice. Mix three tablespoons of juice, coconut cream and arrack. Arrange fruit in the hollowed melon halves. Pour sauce over it. Serve garnished with mint leaves and lime zest.