Lightly grease a 20 x 20cm square baking tin with the vegetable oil and line with an oiled piece of baking paper [see notes].
Pour 375ml of water, the sugar, and lemon juice into a large saucepan and place over a high heat. Stir the mixture as you bring it to the boil.
Once the mixture is boiling, continue to stir constantly until an inserted sugar thermometer reads 115℃ [the soft ball stage - see notes]. Remove the sugar thermometer from the heat and set aside for a moment.
In another large saucepan, add 500ml of water, the cornflour, and the cream of tartar and place over a low heat. Whisk constantly until you achieve a lump free, thick, gluey paste [see photos].
Remove from the heat and gradually add the sugar mixture to the cornflour paste [you might need a friend to help with this!] and whisk constantly until completely combined.
Return the pan to a low heat and simmer for about 1 hour, stirring every 10-15 minutes to prevent the mixture from catching.
Once the mixture has reached a strong amber colour [see photos] add the rose extract and food colouring, and give it a good mix.
Pour the mixture into the prepared tin and allow to set for at least 24 hours - the longer, the better [see notes].
Once the mixture has properly set, combine the icing sugar and cornflour for the coating in a large bowl. Clean a space on your kitchen worktop and dust over a generous amount of the mixture.
Turn out the set Turkish Delight onto the dusted area and carefully peel off the baking paper. Using an oiled knife or pizza cutter, cut into small squares and toss each one in the coating mixture.
The Turkish Delight is best enjoyed fresh and outside in the snow to transport you to Narnia [see notes on storage]