Makes six 6-inch crostatas (serves 6 to 12)
1/2 cup water
3/4 teaspoon fine sea salt
1/2 pound salted butter, cubed and chilled
21/2 cups all-purpose flour
1. In a small bowl, combine the water and sea salt.
2. Place the butter in a separate bowl. Put both bowls in the freezer for 10 minutes.
3. In the bowl of a food processor, pulse together the flour and cold butter about 5 times, or until the mixture has some large chunks and some small. Pulse in the water until the dough just comes together but is not smooth.
4. Dump the dough onto a lightly floured work surface and shape into a ball. Lightly flour a rolling pin. Pat the dough into a rectangle. Roll the dough out to 71/2-by-101/2 inches. With a short end toward you, using a dough scraper, fold the top third down, then fold the bottom third over (like folding a letter to put into an envelope) and rotate 1/4 turn clockwise. Reroll. Repeat three times, lightly flouring the work surface as needed. Wrap the dough tightly in plastic wrap and refrigerate overnight, and up to three days.
5. Divide the dough into six equal pieces and flatten into disks. Chill for 15 minutes. On a lightly floured surface roll each one into a 6-inch round slightly less than 1/8 inch thick. Transfer the rounds to a baking sheet, cover with plastic, and chill for at least 10 minutes. (Dough can be refrigerated up to 24 hours.)