Place cold water in a small bowl and sprinkle with the gelatin. Let stand 1 minute to bloom.
In a standing mixer or blender, mix the sugar, boiling water and gelatin until the gelatin is dissolved. Blot tofu with paper towel. Add the orange juice and tofu and blend until smooth. Refrigerate until mixture mounds slightly when dropped from spoon. Gently fold in cool whip.
Fill 6 dessert dishes with the mixture and chill for 3 or 4 hours or until firm. Garnish with tangerine segments and mint leaves and serve.
Note: Martini glasses filled with the mousse make a nice party presentation.