Heat the oil in a frypan and add the onions, carrots, thyme and cumin; cook for 2 minutes. Add the minced lamb and cook until browned; sprinkle with flour and stir to dissolve.
Add the cranberries, mushrooms and stock and cook for another 5 minutes. Season to taste, then leave to cool. Stir through coriander.
Cut medium-size circles of puff pastry using a cutter. Brush the borders of one of the circles with egg, place 2 tbsp mince mixture on another circle and top it with the first circle, pressing the borders with a fork to seal. Repeat with remaining pastry circles and mixture. Brush each pie with egg.
Place on a baking tray lined with baking paper and cook for 15-20 minutes.
To make a triangle shape, cut the pastry into squares, add the filling and fold in half to form a triangle, pressing with a fork to seal tightly.