Make the dough. In a large bowl, stir together the flours and salt. Add the butter and cut in, using a pastry blender, until pea sized bits remain. Crack the egg and cut it into the mixture. Pour vinegar into ice water and drizzle a little at a time, cutting the liquid into the butter-egg- our mixture until a dough forms. If you squeeze the dough in your hand and it holds, it is ready. Repeat drizzling and cutting in, if it is not ready. On 2 large segments of cellophane, divide the dough and pat it into 2 disks. Wrap snugly and refrigerate for at least 20 minutes to allow the dough to mellow. Use the second disk for another recipe or freeze, wrapped snugly, for up to 3 months. This step can be done up to a week in advance. Combine cranberries, sugars, salt, nutmeg, Grand Marnier, zest and juice, and starch in a medium saucepan. After stirring, let sit until cranberries begin to release their juices, at least 10 minutes. Bring to a simmer and cook over low heat until many cranberries have popped and the mixture becomes jammy, about 10 minutes. Transfer to a heat proof container, cool completely, and cover. This step can be done up to a week in advance. Between lightly oured sheets of parchment, roll dough to 1⁄8” thick, transferring to a baking sheet to chill at any point if the pastry becomes smeary or flabby. Use a round 21⁄2” cutter to cut circles into dough, rolling scraps as needed. Transfer pastry rounds on a baking sheet to chill. Mound 1–2 teaspoons into the center of half the rounds. Brush edges lightly with water, place pastry tops over, then gently press edges together. Use the tines of a fork to make a design around each edge, and the sharp tip of a knife to make small vents for steam to escape. Divide pies between two sheet pans, brush with egg wash and then sprinkle with Demerara sugar. Chill for at least 15 minutes, up to overnight. Preheat oven to 425°F. Bake pies until golden and juices bubbling, 13–15 minutes, rotating pans halfway through for even baking. Transfer to a wire rack and cool until just warm to the touch, or allow to cool fully and enjoy at room temperature.