Wash oranges and slice thinly, discarding the ends. A mandolin is the best tool to get consistent slices, but do use the guard to protect your fingers!
Combine sugar and water in medium saucepan, bring to the boil and let bubble for about 5 minutes to thicken slightly.
Carefully add orange slices - enough so that all are covered by the syrup, return to the boil, then reduce heat to a good simmer.
Cook slowly, for 45-60 minutes, until the fruit and pith is virtually transparent. Try not to move them about too much in the pot or they will break up.
When cooked, turn off heat and cool in the syrup.
When cold, carefully lift the slices one by one, and place on racks, over a tray to catch the drips. Place in a dry airy spot and leave until no longer completely sticky to the touch, but still a little pliable. Mine took about 2 days, but that will vary depending on your kitchen climate.
When dry, dredge in the extra sugar. Store in separated layers, in a container in the fridge - where they should last for at least a month.
