Bring the water and sugar to the boil, stir until the sugar has dissolved. Add the fennel and simmer for several minutes (it should still be crunchy). Remove the pan from the heat, cover and allow to infuse for approx. 6 hours. Drain off the fennel, keep the liquid and use as a syrup.
Spread the fennel slices onto a baking tray lined with baking paper.
Dry for approx. xx hours in the centre of an oven preheated to 80°C.
While the fennel is still slightly sticky, sprinkle with sugar and place in a jar.