Every region of France has its traditional fruit tarts and professional pastry chefs are always inventing variations of their own. It’s all a lot simpler than you might think, because the differences in fruit tarts are easy to understand. First of all, some tarts contain raw fruit, others cooked. Berries, such as strawberries and raspberries, which turn soft and release a lot of liquid when cooked, are usually arranged in a precooked tart shell, the fruit itself remaining raw. This is different from American berry pies in which the fruit is usually combined with cornstarch to thicken the liquid released by the fruit and to try (often unsuccessfully) to prevent the liquid from making the bottom piecrust soggy.