Line a 18cm (7in) square pan with non stick baking parchment and oil the paper.
Place 500ml (18floz) water, 1 tbsp lemon juice and 800h (1lb 12oz) sugar in a heavy based saucepan and bring gently to the boil, stirring constantly until the sugar has dissolved. Once all the sugar has dissolved increase the heat, cover the pan with a lid and allow the mixture to boil for 1 minute.
Remove the lid. Continue to boil the syrup without stirring until the temperature reaches 115°C (139°F). Remove from the heat and set to one side.
Place 125g (4oz) cornflour and 1 tsp cream of tartar in a large saucepan and gradually stir in 500ml (18floz) water a little at a time. Once the cornflour and water have been combined, cook gently stirring with a wooden spoon all the time until the mixture forms a very thick gluey paste.
Remove from the heat and gradually beat in the sugar syrup a little at a time, beating well until smooth after each addition. Do not rush this step.
Return to the heat and bring slowly to the boil, stirring well, then reduce the heat and simmer very very gently for about 1 hour, stirring frequently. Make sure you get into the corners of the pan so that the mixture doesn’t catch. The mixture will turn a golden amber colour when it is cooked sufficiently.
Remove from the heat and stir in 1-2 tbsp rose water and a few drops of pink food colour. Pour the mixture into the prepared tin and allow to set for at least 6 hours.