For the pastry, place the flour, sugar, and salt in the bowl of food processor fitted with the steel blade. Pulse a few times to combine. Add the butter and pulse 10-12 times, until the butter is the size of peas. With the motor running, pour the ice water down the feed tube and pulse just until the dough starts to come together. Dump onto a floured board and knead quickly into a 5-inch round disk. Wrap in plastic and refrigerate for exactly one hour.

Preheat the oven to 400 degrees F. Line a sheet pan with parchment paper.

On a floured board, roll the dough to a rectangle than 10x14 inches. Wrap the dough around your rolling pin, and transfer it to the prepared baking sheet. Use a ruler and a small knife to trim the dough to a 10x14 inch rectangle. Refrigerate for 15 minutes.

To peel the peaches, bring a medium pot of water to a boil. Immerse the peaches in the water for between 15 seconds to 3 minutes, depending on their ripeness. Transfer them a bowl of cold water to cool, then remove the skins. Cut the peaches in half, remove the pits, and cut in 1/2 inch thick wedges. Remove the stem of each fig, and cut into quarters through the stem. remove the pits from the plums, and cut them in 1/2 inch thick wedges.

Place the fruit artfully on the dough in rows. Sprinkle with the full 1/2 cup of sugar and dot with the butter. Bake for 45 minutes to 1 hour, until the pastry is browned and the fruit starts to brown. Rotate the pan during baking. The juices will burn in the pan, but don't worry, the tart will be fine! When the tart's done, loosen it from the pan while it's still warm and transfer to a board.

In a small pan, heat the apricot jelly with 1 tablespoon of water and brush the fruit and pastry completely with the warm jelly. Allow to cool and cut into squares. Serve warm or at room temperature.