Combine rice, John West Herring Fillets, Birds Eye Garden Peas, spring onions, lemon juice and one egg in a large bowl. Season with black pepper.
Cut each pastry sheet in half diagonally and divide mixture between the 4 triangles. Brush one edge of pastry with remaining lightly beaten egg and fold over to enclose filling pressing down and crimping edges to seal. Repeat with remaining pastry.
Place on a baking paper lined tray and brush with egg, cut a vent in the top of the pastry and bake in a preheated oven at 200ºC for 20-25 minutes, or until golden.