Preheat oven to 200°C (390°F). Place the butter, sugar, water and vanilla in a non-stick frying pan over medium heat and stir until the sugar has dissolved. Bring to the boil and cook for 5 minutes, remove from the heat and discard the vanilla bean.
Lightly grease 4 x 8cm round pie dishes with the butter. Place the strawberries in the dishes and pour over the caramel.
Place the pastry on a lightly floured surface and roll out to 5mm thick. Cut 8 x 9cm rounds from the pastry and place on top of the strawberries. Repeat with the remaining pastry. Place the dishes on a baking tray and bake the tarts for 25 minutes or until the pastry is puffed and golden. Turn the tarts out onto plates and top with whipped cream to serve. Serves 4.