1 large tomato, cored and chopped, or 1/2 cup canned diced tomatoes, drained
¼ cup chopped green olives
3 tablespoons raisins
1 teaspoon dried oregano
1 teaspoon salt
½ teaspoon ground black pepper
1 large egg
To make crust, in a large bowl, whisk flour, baking powder, and salt. With a fork or pastry blender, cut in the lard or shortening, working quickly, until the mixture resembles coarse crumbs.
Drizzle the water over and blend it into the flour mixture, until the dough begins to hold together (if it doesn’t, work in another tablespoon or so of water). Turn dough out onto a lightly floured surface and knead gently 1 minute. Cover with plastic wrap and let rest 30 minutes. (To make dough ahead of time, cover and refrigerate for up to 2 days; bring to room temperature before using.)
Meanwhile, prepare filling: In a large skillet, heat oil over medium-high heat. Add onion and garlic and cook, stirring, until soft, 5 minutes. Add beef and cook, stirring to break up meat, until no longer pink. Stir in tomato, olives, raisins, oregano, salt, and pepper; bring to a boil, stirring occasionally.
In a small bowl or cup measure, whisk cereal and water together to make a slurry. Gradually pour into bubbling beef mixture, stirring, until thickened, about 5 minutes. Remove from heat and let cool.
To assemble empanadas, preheat oven to 400°F. Grease 2 baking sheets. In a small bowl, beat the egg and 1 tablespoon water together and set aside.
Roll dough into a log and cut it into 12 pieces. Roll each piece into a 6-inch circle.
Place about 2 tablespoons of the filling on the top halves of each dough circle, leaving ½-inch border. Moisten the edges with a little water, then fold each circle over and seal, crimping the edges with the tines of a fork. Brush the filled empanadas with the egg mixture, and place 2 inches apart on the baking sheets. Bake until golden brown, about 15 minutes. Let cool 10 minutes before serving.