For the berries: In a small bowl, toss the strawberries with the sugar and vinegar. Let the mixture stand at room temperature, stirring occasionally, for 2 hours.
For the whipped cream: In a medium bowl, beat the heavy cream until it forms soft peaks. Add the powdered sugar and vanilla. Continue to beat until the cream holds stiff peaks.
To serve: Spoon the strawberries and juices into 2 small glasses and add a dollop of whipped cream. Sprinkle with chopped mint and serve.