In a large bowl combine the pre-cooked lamb, onion, garlic, potato and spices.
Prepare the barbecue for indirect cooking over indirect medium heat (180-230°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 semi-circle. Press down on the edges to create a seal. If desired, crimp the edges. Place onto 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 for 25 minutes per tray.
Serve with tomato sauce or chutney.