1. In a food processor, pulse the flour with 2 tablespoons of the sugar and salt. Add half of the butter and pulse several times, and add the rest. Pulse just until it is the size of peas. Add the ice water and pulse a few more times just until Mixture holds a non crumbly clump. Turn the crumbs out onto a work surface and pat the pastry into a disk. Wrap the pastry in plastic and chill overnight in refrigerator (or at least 6 hours), or freeze for 1 month.
2. Meanwhile, peel the blood oranges, removing all of the bitter white pith. Thinly slice 2 of the oranges crosswise; remove the pits. Transfer the orange slices to a plate. Working over a sieve set over a bowl, cut in between the membranes of the remaining oranges, releasing the sections into the sieve. Remove the pits and gently shake out as much juice as possible without mashing the sections; you will need 1 cup of sections. Reserve the orange juice
3. Allow dough to come to room temp. On a floured work surface, roll out the pastry to an 11-inch round with a pin. Dust the center circle with a mixture of 1T flour, and 1T sugar (will prevent the galette from having a “soggy bottom”).
4. Arrange the orange sections on the pastry, leaving a 2-inch border all around. Sprinkle the 2 tablespoons of granulated sugar over the oranges and drizzle 1 T melted butter. Fold up the pastry over the oranges, leaving most of the oranges uncovered. Brush the pastry with the egg wash and sprinkle lightly with 1 tablespoon of the raw sugar. Arrange the orange slices on top, leaving a 1-inch border of pastry all around. Sprinkle the remaining 1 tablespoon of sugar on top and drizzle the remaining egg wash on top. Freeze the tart until solid, at least 4 hours or preferably overnight.
5. Preheat the oven to 375° and position a rack in the center. Place a baking sheet on the rack below to catch any drips. Bake the tart directly from the freezer for 1 hour and 15 minutes, until the fruit is bubbling and the pastry is deeply browned. Transfer the cookie sheet to a rack and let the tart cool for 30 minutes. Carefully slide the parchment paper onto the rack and let the tart cool completely.
Serve with the Dark Salted Butter Caramel Sauce (below).