-(optional) Pre-heat the oven to 220 C, 230ºC , Gas mark 8. Drain can of salmon, reserve the juice. Set aside. Roll out pastry to 0.5cm / 1 cm thick. Cut into four 8.5cm / 8 cm rounds. Stand, rolled side down on a dampened baking tray for 30 minutes. Brush upper surface with milk. Bake for 10-15 minutes until golden. Cool. Sprinkle cucumber with quarter teaspoon salt, leave 15 minutes. Melt butter in a saucepan. Stir in flour, then salmon juice and milk. Bring to boil. Mix well. Add rinsed cucumber, cream, tarragon and salmon. Blend well. Cut each pastry round into three slices crossways. Pile half salmon filling onto bottom slices. Place middle layers on top and remaining filling over these. Top with puff pastry tops. Serve hot with vegetables. Serves 2. Approx. 800 kcals per serving