To make the Chimichurri sauce: In a small bowl, whisk together ⅓ cup of olive oil with 1 tablespoon of red wine vinegar, lemon juice and 2 tablespoons of Chimichurri, then set aside for the flavours to develop.
Dice the onion, crush the garlic and heat 2 tablespoons of oil in a large saucepan over MED – HI heat. Add the onion and garlic, cook for about 3 minutes or until softened.
Add the beef, the ancho chilli and the remaining tbsp of Chimichurri, cook until the meat has browned.
Stir in the tomatoes, the remaining tablespoon of red wine vinegar, the tomato paste and olives, then bring to a simmer. Cook for about 5 minutes, until the filling has thickened slightly, then remove from heat.
Preheat the oven to 200°C, line a baking tray with non-stick paper.
With your cutter (you can use any glass or cup with a 9cm diameter) cut your rounds from the puff pastry.
In a small bowl, beat the egg with a fork. Spoon about a tablespoon of the filling into the middle of each pastry round, then fold the pastry in half to make a semi-circle. Press the sides with a fork and then brush the tops of the empanadas with the beaten egg.
Bake in the oven for 25 minutes or until golden brown.