Caramel flan

Preheat the oven to 170C/Fan 150F/Gas Mark 3. Place 175g/6oz of the caster sugar in a pan, gently heat, stirring occasionally until the sugar dissolves. Carefully add the lemon juice and stir until the bubbling stops. Pour over the base of a 900ml/2pt round heatproof dish, swirl to spread the caramel over the base and sides. Set aside. Add the milk to the caramel pan with the lemon and orange zest. Slowly bring to the boil. Leave to cool, then strain and discard zest. Beat the eggs and remaining sugar together, beat in the milk. Pour the egg mixture over the caramel lined dish. Place in a roasting tin; pour boiling water from the kettle to come halfway up the outside of the dish. Bake for 35-40 mins or until just set but still a little wobbly in the centre. Cool. Chill for at least 4 hours. Meanwhile, segment the orange and reserve. To serve invert the pudding onto a serving plate; cut into wedges and serve decorated with the orange segments.