Peel the skin from the mango and cut the mango off the pit. Cut the mango into 1-inch pieces to yield 1 cup.

In a small bowl, place ¼ cup grape juice. Sprinkle in the gelatin and stir to mix. Let stand for 1 minute. In a small saucepan, heat the remaining ½ cup grape juice until hot. Pour the hot grape juice into the juice/gelatin mixture and stir until the gelatin is completely dissolved. Let cool but not set.

In a blender, place the mango and sugar and blend on high speed until smooth. Add the sour cream, whole milk, rum, lime juice, and gelatin/grape juice mixture and blend well.

Pour into four 8-ounce soufflé dishes. Cover with plastic wrap and chill until firm, about 4 hours or longer.

If desired, this dessert may be served with heavy cream or condensed milk poured over the top and garnished with 2 mint leaves for each serving.