To make the pastry, combine the dry ingredients in a largebowl. Add the butter and work it into the flour mixture with your fingertipsuntil it resembles small peas. Form a well in the mixture and add the egg yolksand milk. Combine, turning the dough out onto a lightly floured board to mixcompletely. Form the dough into a ball, cover it in plastic wrap and allow itto rest for at least half an hour.
Meanwhile, make the filling: Cut the onions in half; peel them and slice them thin. In a large sauté pan, melt the butter and add the onions, cooking them gently until soft and sweet. Season generously with oregano and salt; let cool.
Half an hour before you’re ready to cook the empanadas, heat the oven to 425°F and line a baking sheet with parchment paper. Roll out the dough to a thickness of ¼-inch and use a 4-inch cutter to form as many rounds as you need. Spoon a generous tablespoon of sautéed onions into the center of each round, sprinkle with chopped egg, and then fold the dough over, crimping the edges together to seal the empanada. If you like, beat an egg with a tablespoon of water and brush the mixture onto the empanada; it will give it a glossy shine. Place the empanadas on the baking sheet and bake them for 35 to 40 minutes, until golden brown. Serve with a fresh Uco Valley malbec.
