In a large bowl combine the lamb, onion, garlic, potato, and spices.
Prepare the barbecue for indirect cooking over medium heat (180° to 230°C). If using a Weber Q barbecue, set up your barbecue with a convection tray and a trivet.
Cut four 12cm-diameter rounds from each sheet of the pastry. Spoon 1 tablespoon of the filling onto the centre of each pastry round. Fold the pastry over to create a semicircle. Press down on the edges to create a seal. If desired, crimp the edges. Place onto a lined baking tray. Pierce the pastries with a fork to let any steam escape.
Brush the empanadas with the beaten egg and bake the empanadas over indirect medium heat, with the lid closed, for 25 minutes per tray.
Brush the empanadas with the beaten egg and bake the empanadas over medium heat, with the lid closed, for 25 minutes per tray.