2) Meanwhile, put 175ml of the cream, the yoghurt, vanilla essence and the vanilla bean seeds in a medium bowl and whisk together.
3) Heat the remaining 175ml of cream and the sugar in a small saucepan and bring to a simmer over medium heat. Remove from the heat, add the softened gelatine to the hot cream and stir to dissolve.
4) Pour the hot cream-gelatine mixture into the cold cream-yoghurt mixture and stir to combine. Pour into 4 (0.2L) ramekins or custard cups and refrigerate uncovered until cold.
5) When the panna cottas are thoroughly chilled, cover with cling film and refrigerate overnight.
6) Around 30 minutes to 1 hour before serving, combine the strawberries, balsamic vinegar, sugar and black pepper. Set aside at room temperature.
7) To serve, run a small knife around each dessert and dip the bottom of the ramekin quickly in a bowl of hot tap water. Invert each ramekin onto a dessert plate and surround the panna cotta with strawberries. Dust lightly with freshly grated lemon zest and serve.