Bitter-Orange and Blueberry Tart

Ideally, this should be made with bitter Seville oranges, but since they are available for only one month of the year and ordinary oranges are around all the time, it seems reasonable to have sweet eating oranges as the first choice, adding the juice of a lime in order to reproduce as closely as possible the fragrant bitterness of Sevilles.

I find this easiest to do over a few days; one, because the taste is so much better when the juice and cream and so forth are left to deepen in