It's only the beginning of kumquat season so they are still hard to find (or expensive). But I've been having a craving for bitter citrus marmalade. The closest thing I can find right now is calmondins (aka calamansi) which I finally decided to experiment with. I received a Buddha's Hand in my CSA this week, so I decided to improvise and make a Calamondin & Buddha's Hand marmalade. I also used the juice of half a dozen clementines.
It was a small batch and I cooked it in my large jam pot, and it was the fastest marmalade I've ever made. It was set in less than 30 minutes.