Cut each apricot half into four slices.
Place the apricots, pitted cherries, amaretto, lemon juice, salt and 50 g (¼ cup) sugar in a medium saucepan, stir and let sit for 10 minutes to draw some water out of the fruit.
Whisk together 50 g (¼ cup) sugar and the cornstarch in a small bowl until combined and set aside.
Bring the fruit mixture to a light simmer over medium heat while stirring gently. Simmer, stirring occasionally, until the fruit has just softened, about 6-8 minutes.
Add the cornstarch mixture and stir. After a few minutes, it will start to thicken and a few bubbles will pop.
Cook for 1 full minute after you see the first bubble. Scrape the filling into a bowl, cover it and chill it for at least 2 hours or until completely cold.
Heat the oven to 375 degrees Fahrenheit with a rack in the oven’s lowest position.
Add flour, powdered sugar, rice flour and salt into the bowl of a food processor. Pulse five times to combine.
Add the cubed butter to the food processor and pulse until the mixture resembles fine breadcrumbs, about 10-15 one-second pulses.
Add the egg, water and vanilla extract to the food processor and pulse until the dough starts to come together into a ball and holds together when squeezed, about 10-15 one-second pulses.
Dump the dough onto the counter and gather it into a ball. Divide the dough in half.
Press one piece of dough into a ½-inch-thick square, wrap it in plastic wrap, and chill it in the refrigerator until needed.
Line the tart pan: Take the second disc and press it into a 9½-inch round, 1-inch deep tart pan with a removable bottom, making sure the dough is an even ⅛-inch thick around the bottom and the sides.
Trim off any excess dough that extends above the rim of the tart pan. Put the tart shell in the freezer for at least 15 minutes to firm up.
Remove the tart shell from the freezer and the filling from the refrigerator. Sprinkle the bottom of the pastry with rice flour or breadcrumbs.
Pour the filling into the lined tart shell and spread it evenly.
Remove the square of dough from the refrigerator and dust it with flour. Roll the dough about ⅛-inch thick.
Cut 1-inch-wide strips of pastry dough using a pizza wheel or a long chef’s knife and a ruler.
Dampen the rim of the crust with a bit of water, which will help the pastry strips adhere.
Place the strips of pastry parallel to each other, with about ½ inch of space between them, on top of the pastry, and press the edges lightly to adhere.
Place another row of pastry strips at a 45-degree angle from the first row of strips to create a diamond-like pattern.
Trim off the excess pastry using your fingers or a paring knife.
Make the egg wash by whisking together the egg and salt.
Brush the top crust with the egg wash and sprinkle with turbinado sugar.
Transfer the tart to a baking sheet to catch any drips.
Bake on the lower rack of the oven at 375 degrees Fahrenheit until deep golden brown on top, about 42-46 minutes.
Take the tart out of the oven and carefully remove it from the baking sheet and place it on a wire rack to cool.
Cool completely. Remove the crostata from the tart pan and put it on a serving platter.
