Chill two bowls.
Place water in small saucepan, sprinkle gelatin over water and let soften about 10 minutes.
Stir mixture over low heat until dissolved, then remove from heat.
Let cool but not set, about 10 minutes.
Place sour cream in one of the chilled bowls and stir in gelatin mixture. Set aside.
In the other chilled bowl beat whipping cream, sugar, and vanilla, until soft peaks form.
Fold into sour cream mixture in two parts.
Cover and chill at least one hour.
Garnish with mint leaves.