1. In a small bowl, sprinkle the gelatin on three tablespoons of cold water. Stir and set aside for 10 minutes to allow the gelatin to dissolve.

2. Meanwhile, whisk together 1 1/2 cups of the cream, the yogurt, the vanilla extract, and the vanilla bean seeds. Heat the remaining 1 1/2 cups of cream and the sugar in a small saucepan and bring to a simmer over medium heat. Off the heat, add the softened gelatin to the hot cream and stir to dissolve. Pour the hot cream/gelatin mixture into the cream/yogurt mixture and stir well to combine. Pour into eight (3 1/2" round ? 2" high) ramekins or custard cups and refrigerate uncovered until cold. When the panna cottas are thoroughly chilled, cover with plastic wrap and allow to set overnight.

3. Thirty minutes to an hour before serving, combine the strawberries, raspberries, blueberries, balsamic vinegar, sugar, and pepper. Toss well and set aside at room temperature.

4. To serve, run a small knife around each dessert and dip the bottom of each ramekin quickly in a bowl of hot tap water. Unmold each ramekin upside down onto a dessert plate and surround with mixed berries and their juices. Dust lightly with freshly grated lemon zest and serve.