Blend flour, salt and pepper in a food processor. Add the egg and pulse, then add the butter and pulse until combined.
Slowly add the water, mixing in for approximately 10–15 minutes on a slow speed, then finish on a high speed for 1–2 minutes.
Cover the dough with cling film and allow to rest on top of the oven for 1 hour before use.
Boil the potatoes in a large pot of water for 10 minutes or until they are soft. Drain the potatoes and set aside.
Melt butter in a frying pan and saute onion and capsicum.
Add the beef, cumin and paprika and cook until any liquid has evaporated and the mixture is quite dry.
Add the salt and pepper and continue to cook for another 3 minutes.
Add the potatoes and flour and cook for a further 3 minutes.
Take the frying pan off the heat and add green onion and olives and stir to combine.
Pre-heat oven to 190°C.
Divide the pastry into 4 pieces and roll each piece out until about 3mm thick. Using a 14cm cookie cutter, cut the dough into circles.
Place 2 tablespoons of filling into the centre of each circle. Gently wet the edges of the pastry and fold over to make a semi-circle. Fold the edges into pleats or seal by pressing down with a fork. Repeat with remaining dough and beef filling.
Place empanadas on a baking tray and bake in the oven for 25–30 minutes or until the pastry is crispy. Serve immediately.