2 1/2 cups flour (I like to swap out 1/2 cup whole wheat flour, but that's optional)
1 pinch salt
zest of 1 orange
1/2 pound cold unsalted butter, cut into pats
~1/3 cups orange juice (you can squeeze this from the orange you zested)
3 tablespoons olive oil
1 yellow onion, sliced into thin half-moons
3 cloves garlic, thinly sliced
2 teaspoons pimenton (smoked spanish paprika), sweet or hot
1 pinch chili flakes (omit if using hot pimenton)
1/2 cup tomato puree
1/2 small cauliflower, broken into small florets
2 5-ounce cans oil-packed tuna, drained
1/4 cup drained capers
1/4 cup chopped parsley
1 splash sherry vinegar
2 sprigs fresh thyme (leaves only)
salt and pepper to taste
In a large bowl, mix together the flour, salt, and orange zest. Add the butter, toss to coat with flour, and press down with the heel of your hand to flatten it into flour-coated flakes. Stir from the bottom to distribute, and repeat the pressing and stirring process until all of the flour is incorporated into flakes or bits. Add the orange juice, and work the dough until it just comes together (you'll work it more later, so no need to go nuts—smears of butter are fine). You may not need all of the orange juice, or you may need more, depending upon your dough. Wrap in plastic and refrigerate for 20-30 minutes.
While the dough is chilling, prepare the filling. Heat the oil in a large skillet over a medium-high heat. Saute the onions about 7 minutes, until beginning to soften, then add the garlic and saute another 2 minutes. Add the pimenton and chili flakes, stir to toast, then add the tomato puree and cauliflower. Cover and cook until the cauliflower barely begins to lose its rawness but is still plenty snappy—just a minute or two. Turn off the heat, and add the remaining ingredients. Place in the refrigerator to chill.
While the filling is chilling, take out the dough out of the fridge, and unwrap on a lightly-floured countertop. Roll out to a rectangular shape, then fold like an envelope and rotate 90 degrees. Repeat twice more, then re-wrap and return to the fridge for another chill, ~30 minutes.
Preheat the oven to 400 degrees. Line two baking sheets with parchment, and prepare your egg wash.
When the dough has chilled, remove from the refrigerator, and let soften for a few minutes. Roll out thinly, and cut out 6" circles (if you, like me, don't have a 6" cutter or bowl to use, you can just use a 4" cutter, and then roll them out further, or divide the dough into 10 pieces, and roll each one into a round). Scoop 1/4 filling onto each round, and brush the edges of the dough circles with the egg wash. Fold over to make a half circle, securing the seal by pressing with your fingers or crimping with a fork. Place the filled turnovers on your baking sheets, brush with the egg wash, and cut a couple tiny holes for the steam to vent. If the kitchen is quite warm, you might need to chill them for a bit after this step, but ordinarily you can transfer them right into the oven (If you're making a bunch in advance, you can freeze them at this stage, and just add a few extra minutes to the baking time when you do cook them). Bake until browned and bubbling, ~30 minutes. Devour.