Place flour in food processor, add cold butter cut into pieces and process until fine crumbs. Add sour cream and salt and start motor again. Gradually add water through the chute with motor running. As soon as pastry forms a ball tip out and pat into a flat disc. Wrap in plastic wrap and refrigerate until needed.

Preheat oven to 200°C. Divide fish mixture amongst 8-10 buttered dishes, such as soufflé dishes shown in photo which have a one cup (250ml) capacity. Fill almost level with the top. Roll out pastry on a floured surface and cut circles the diameter of dishes plus 2-3cm. Dampen edges of dishes, place pastry circles on top and press pastry on to seal. Cut a hole for steam to escape. Brush with beaten egg then bake for 30-40 mins or until golden brown and bubbling through the steam vent.