Apple-Prune Galette

Prepare a hot fire (450F) in a wood-fired oven or cooker.
To make the dough, combine the flour, salt, and sugar in a bowl.
Stir with a whisk to blend.
Using your fingertips or a pastry blender, rub or cut the butter into the flour until some of the butter is in flakes and the rest is the size of peas.
Stir in the water 1 tablespoon at a time to moisten the dry ingredients.
Form the dough into a ball.
It will still look a little rough with some streaks of butter.
On a floured board, divide the dough into 2 pieces, flatten each piece into a disk, and wrap in plastic.
Refrigerate for at least 1 hour or up to 3 days.
Freeze the extra disk of dough for up to 1 month.
To make the filling, cover the prunes with hot water and let soak for 15 minutes.
While the prunes soak, peel and core the apples and cut them into 1/8-inch slices.
Drain the prunes.
Put them in a bowl with the apples and toss with the sugar and liquor.
On a floured board, roll 1 disk of the dough out into a 14-inch round.
Transfer the disk to a cornmeal-dusted pizza peel.
Mound the fruit in the middle, leaving a 2-inch border of exposed dough.
Fold the dough over the fruit, pleating it to close as you go around.
Sprinkle the folded-over dough with the 1 tablespoon of sugar.
Slide the galette from the peel directly onto the hearth of the wood-fired oven.
Bake until the crust is brown and the apples yield to the tip of a knife, 25 to 30 minutes.