So much depends on the plums for a tart, they should be almost bursting at the seams with juice. Their season is short, but when the moment strikes, a rare treat awaits with this simple tart — the dough is like a sugar cookie, with only the butter holding it together. I suggest a ring of whipped cream inside the rim of the tart as an optional decoration.
1 1/2 lb/675 g purple plums (about 1 quart/1 liter)
2/3 cup140 g sugar
For the pastry dough
1 cup/125 g flour, plus 2 tablespoons during mixing
1/4 cup/60 g sugar
1/2 cup/110 g butter, cut in dice
1/2 teaspoon salt
Grated rind of 1/2 lemon
9-inch/25-cm tart pan with removable base or shallow spring-form cake pan
1. Heat the oven to 425ºF/220ºC and set a shelf in the center. Wash and drain the plums, halve them and discard the pits. Set them, cut side down in a single layer in a shallow baking dish. Sprinkle them with the sugar. Cook them in the oven so the juice runs freely, 12-15 minutes. Set them aside to cool. Lower the oven heat to 350ºF/175ºC.
2. For the pastry dough: put the flour, sugar, butter, salt and lemon rind in a bowl. With your fingertips rub the ingredients together to form crumbs, then press them together into a ball of dough. Knead the dough in the bowl for 15 minutes, working in 1-2 tablespoons more flour as necessary — the dough is rich and sticky. It can also be mixed and kneaded with the dough hook of an electric mixer, allowing 3-5 minutes.
3. Tip the dough into the tart pan (it does not need to be greased) and press the dough over the base and sides of the pan with your fist, making a rim of 3/4-inch/2-cm high and about 3/8 inch inch/1 cm thick. Arrange the cooked plums, cut side up in concentric circles on the dough, reserving the syrupy juice. Bake in the oven until the crust is lightly browned, 30-35 minutes.
4. Take the tart from the oven and let it cool. Stir the plum juice over medium heat, simmering it until syrupy, 3-5 minutes. Take care as it burns easily. Spoon the syrup over the plums.