Combine sugar, vinegar, pinch of salt and a few grinds of black pepper in a bowl. Mix well to incorporate. Let stand for 15 minutes.
In the meantime cut the pears (skin on) into thin wedges with the seeds and stem removed. A good trick is to halve the fruit then use a melon-baller to scoop out the seeds then trim away the small bit of stem.
Place pears in a mixing bowl and carefully mix. When the balsamic-sugar mixture is ready, pour over the fruit and mix gently to coat evenly. Gently crush the biscotti into 6 serving bowls. Divide the pears into each dish then top with a dollop of the mascarpone cheese or a scoop of caramel or cinnamon flavored gelato or ice cream. Serve immediately.