Put the blackberries in a bowl, add 3 tablespoons of the sugar and lightly crush. Stir gently until the sugar has dissolved. In another bowl, stir the remaining sugar into the yogurt, then add 1-2 tablespoons of the crushed blackberries. Swirl lightly to marble.
Arrange the meringues on plates, add a big dollop of the yogurt, then a smaller dollop of lemon curd. Top each with the remaining blackberries and decorate with mint.