Put the sugar, cardamom pods, saffron and lemon juice in a wide, shallow pan with the water. Stir to dissolve the sugar and bring to a simmer.
Peel the pears, halve and core them, and immediately put them into the simmering syrup. Cover with greaseproof paper and the lid of the pan and cook gently for 20-30 minutes, spooning the syrup over the pears every now and then.
Carefully remove the pears and arrange in a single layer in a serving dish, cut side down. Pour the syrup over them and allow to cool.
Chill in the fridge and serve very cold. These keep for several weeks, covered, in the fridge.