Line a 20 to 25cm square cake pan or lamington pan with non-stick baking paper. Brush the paper with a very light coating of vegetable oil.
Put the sugar, hot water, cardamom pods, lemon juice and salt together in a large saucepan. Heat without boiling, stirring constantly, until the sugar has dissolved completely.
Sift the gelatine and 1 1/2 tbs cornflour together into a bowl. Add the cold water and mix to a paste. Pour in some of the sugar syrup and stir with a whisk until smooth. Add the remaining sugar syrup and stir again.
Return the mixture to a clean pan and bring slowly to a boil, stirring constantly with a wooden spoon. Reduce to a simmer and cook for 20 mins, stirring frequently to prevent the mixture sticking to the bottom of the pan. It will thicken slightly and become a pale golden colour.
Remove from the heat and leave for a minute to allow the bubbles to subside. Skim off any foam or skin that forms on the surface and remove the cardamom.
Add the saffron infusion and orange blossom water and stir to combine.
Pour into the prepared pan. Allow to cool completely and leave in a cool, dry place overnight (do not refrigerate) before cutting.
Sift together the icing sugar and extra cornflour. Dust a cutting board with this mixture and turn out the Turkish delight onto the board. Use a large sharp knife very lightly brushed with oil to cut into small squares.
Toss the pieces in the icing sugar mixture to prevent them sticking together. Store them, generously coated with icing sugar, in a lidded container at room temperature.