Place the strawberries, raspberries and blueberries in a food processor or blender and process until smooth.
Press through a fine nylon sieve into a large measuring jug to remove the pips and blueberry skins. Stir in the balsamic vinegar, then chill for 30 minutes.
Meanwhile, place the sugar and water in a small saucepan over a high heat. Stir until the sugar dissolves. Bring to the boil, without stirring, and boil for 5 minutes until a light syrup forms.
Pour into a heatproof bowl and leave to cool, then stir in the pureed berry mixture and leave to chill until required.
Add the whipped cream to the berry mixture in the bowl, and fold in gently.
Pour into an ice-cream machine and freeze according to the manufacturer’s instructions. Then transfer to a freezer proof container and freeze for at least 2 hours before serving. If you do not have an ice-cream machine, pour the mixture straight into a larger freezer proof container and freeze for 1 hour or until set round the edges.
Beat until the mixture is smooth, then return to the freezer. Freeze for 30 minutes, then beat again. Repeat the freezing and beating several times more until the ice cream has a smooth consistency, then leave it to freeze for at least 2 hours.
To make the strawberry compote, slice the berries into a serving bowl. Sprinkle with sugar to taste, then add a splash of balsamic vinegar and a little freshly ground black pepper. Stir, then chill until ready to serve.
Transfer the ice-cream to the fridge 20 minutes before serving to allow it to soften. Scoop into individual bowls and top with the strawberry compote.
Decorate with sprigs of mint and serve.