Finely chop mushrooms by hand, or alternatively, pulse in a food processor until finely chopped.
Heat 1 tbs oil in a large saucepan over medium heat. Add onion, sauté for 3 minutes or until softened. Add curry powder, cook, stirring for 1 minute. Add mushrooms, increase heat to high and cook for5 minutes or until moisture has almost evaporated.
Add mince, cook, breaking up mince with wooden spoon until mince changes colour. Sprinkle over flour, stir until well combined. Stir in stock and kumara, bring to the boil. Reduce heat to medium, simmer, uncovered for 8 minutes or until kumara is tender and mixture is thick. Set aside to cool. Stir in peas.
Place an oven tray into the oven. Preheat tray and oven to 220°C. Lightly grease 6 x 8cm base measurement pie pans. Cut 1 x 20cm circle from each sheet shortcrust pastry. Use to line bases and sides of pans. Divide mince mixture between pie tins. Fold excess pastry over filling to partially cover. Brush pastry with water and season. Place pies onto hot tray. Bake for 20-25 minutes or until golden. Serve.