"These turned out wonderfully! I left the entire pith on and blanched them 3 times, and I don't detect any bitterness at all. I think how bitter they are depends on the oranges you use. I used in-season Florida oranges from a local grove. They were juicy and delicious, so the peels are now sweet and chewy. This is a very easy recipe, it's just very time consuming when you consider peeling, chopping, boiling a pot of water 3 times, cooking the sugar, and then simmering the peels. It took me about 5 hours total, but it was worth it :)