If you aren’t familiar with Calamondins, they look like a miniature tangerine or Clementine, and have the same thin, pliable skin that easily detaches from the fruit. But unlike Clementines, the pulp of a Calamondin is tart, with a bitter edge, which is of course why they’re so perfect for marmalade.
Several friends suggested that the juice would be a perfect substitute for that of bitter oranges in marinades for such things as Cuban style pork roast, or hearty roasted fish such as grouper or snapper. But using only the juice meant wasting those beautiful, vibrant skins, and since the day was cool and clear—ideal for making preserves—why quibble with marmalade just because it’s obvious?
When it comes to marmalade, the old-fashioned kind, with a nice bitter bite to cut the sweetness, is best. And for that, we need look no further than Lettice Bryan’s 1839 masterpiece, The Kentucky Housewife:
Grate fine the yellow peel from some ripe deep colored oranges, cut up all that are decorticated, saving the juice and removing the seeds and cores; mix with the pulp the grated peel, add an equal weight of powdered loaf sugar and a very little water, simmer the whole together till it becomes thick and quite transparent. When cold put it up in small glass jars, and cover them with brandy papers.”
The delicate skins of Calamondins would not have taken to grating, but Mrs. Bryan’s formula otherwise made better sense than the things that had turned up on the Internet. The pitted fruit was sliced and tossed into the pot without separating the skins. The only addition to her sensible recipe was a tiny pinch of salt to brighten the flavor.
Calamondin Orange Marmalade
Wash the oranges and carefully twist off the stems (don’t pull or their delicate skins will tear). Weigh the fruit, then halve, seed, and thinly slice it, conserving all the juices. Toss the fruit and its juices into a heavy-bottomed stainless steel or enameled pot as it is cut.
Add an equal weight of sugar, a scant cup of water for each pound, and a small pinch of kosher or pickling salt. Stir until the sugar is mostly dissolved, then bring it to a boil over medium heat, stirring often. Maintain a steady boil and cook until the skins are transparent and tender and the syrup is thickened and jellies when dropped from the spoon onto a saucer (210-220 degrees F. on a candy thermometer). It will take about half an hour or a little more.
Let the marmalade cool slightly, then using a perfectly clean stainless or silver ladle and wide-mouthed funnel, transfer it to sterilized half-pint jars. Cover with new canning lids, cool, and refrigerate or, for prolonged storage, process in a water bath for 5 minutes.