(Las Empanadas de Carne de Matilde)
These classic savory Argentine pastries are filled with an egg, beef and olive stuffing.
1. For the filling: Bring a medium pot of salted water to a boil, add onions, and cook over medium heat until soft, 10–15 minutes. Drain; then return onions to pot. Add beef, butter, oil, beef fat, oregano, sugar, flour, peppers, and salt to taste. Cook over medium heat, stirring often, until meat is cooked through but not browned. Adjust seasonings. Transfer to a bowl, let cool, cover, and refrigerate for at least 2 hours or overnight.
2. For the dough: Dissolve salt in 2 cups water in a small bowl. Combine flours, 1 cup of the cornstarch, powdered milk, and baking powder in a large bowl. Work beef fat and half the butter into flour mixture until it resembles fine meal. Mix in half the salt water. Continue mixing, adding more salt water, little by little, until a rough dough forms. Transfer to a lightly fl oured surface and knead until smooth. Wrap in plastic wrap and refrigerate for 1 hour. Melt remaining butter in a small pot. Divide dough into 10 equal pieces. Roll 1 piece out on a clean surface into a 7" x 11" rectangle. Brush with butter, dust with cornstarch, fold lengthwise, and roll out to a 1/16" thickness. Using a 4 1/2" round cookie cutter, cut out 3 disks, discarding scraps; dust disks with cornstarch, stack, cover with plastic, and set aside. Repeat with remaining dough, butter, and cornstarch.
3. Move oven rack to top third of oven; preheat oven to 400°. Put 1 dough disk on a clean surface, add 1 tbsp. of filling to center, top fi lling with 1 olive and 1 egg wedge, and fold disk into a half-moon shape. Press and pleat edges together to seal. Repeat process with remaining disks, filling, olives, and eggs. Place empanadas on baking sheets at least 1/2" apart, then brush with beaten eggs. Bake on top rack of oven until golden and hollow sounding when tapped on bottom, 25–30 minutes.