Calamansi: A Petite, Intensely-Flavored Citrus

Watch out, yuzu: Calamansi is coming for you. In the ever-fickle focus of the trend-obsessed digital culinary world, fragrant yuzu remains, for now, the darling of internet searches (according to my quick query on Google Trends). But curiosity about calamansi, a small, sour, sweet-skinned citrus, is piquing. If not peaking (sorry). Possibly native to China, but ubiquitous in the Philippines and Indonesia, this petite citrus is widely cultivated in Southeast Asia. There, it is often harvested when mature but still green, with an interior that is already bright orange. It is far less common Stateside, where the fruit is also known as calamondin. Here, ripe yellow-skinned calamansi is available seasonally from a handful of specialty growers, and the trees are available to buy from some growers. They can be grown in pots, or planted in-ground. They bear fruit around year four.

Here’s what to expect from calamansi, and how to use this aromatic and tart citrus.

Photography by Marie Viljoen.

Calamansi-slash-calamondin has many other common names, including must lime and Philippine lime. Botanically, it is Citrus x microcarpa, and is thought to be a natural hybrid: Its tart interior speaks kumquat; its aromatic skin, mandarin.

Calamansi has a thin skin and minimal pith, like a Meyer lemon. Despite its tiny size, it is intensely juicy. Its copious seeds are reminiscent of yuzu (and, like yuzu’s, they are used in folk remedies as well as commercial skincare products).

Calamansi trees seem to be one of the less demanding citrus* to grow in cold climates. While the tropical tree must be overwintered indoors in climates colder than USDA growing zone 10, it seems happier with less than the usual prescribed full sun (which means a minimum of six hours, uninterrupted, a hard condition to meet indoors). My own tree was inherited last year from a friend who left Brooklyn to travel the world, and in her apartment it spent its green, lush life facing a very bright exterior wall, with no direct sun at all. It did not bloom or fruit. But leaf out, it did. On my summer terrace it flowered minimally, but made no fruit. I think more sun outdoors this year will produce better results. (Other city growers have the opposite problem.)

* More demanding indoor citrus? Meyer lemons, hands down. (Another citrus that requires less sunlight, since it is also a forest tree, is Thai lime, or makrut—Citrus hystrix.)

Like all potted citrus, calamansi grown in a container needs exceptional drainage. I use a 50:50 mix of potting soil and cedar shavings (shredded cedar mulch also works). Plant the tree in a pot only an inch or so wider than the grow-pot it arrived in. If the pot is too big the soil tends to stay moist too long, and too much moisture is death to most indoor plants. Water deeply, meaning: until the water runs from the drainage holes. Never allow the pot to sit in a pool of water. And water again when it is almost dry. This may take a week or more. A moisture meter is very helpful. The ideal spot for a citrus tree is in the sunniest window you have. Failing that, bright natural light will ensure healthy green leaves, but possibly not flowers and fruit.

For an in-depth primer on citrus in pots, see: 14 Things Nobody Tells You about Indoor Citrus Trees

If you are lucky enough to have a citrus-growing neighbor like garden designer Rachel Prince, whose citrus collection lives a few blocks from mine, you may score some ripe calamansi in winter. Increasingly, specialty growers are also selling them. (You can buy the fruit seasonally online from Flavors by Bhumi.) The trees are available from Four Winds Growers, where an 18-36-inch tall calamansi is $60.

So you have a clutch of calamansi. Now what? Certainly, it is all about the juice (this is not true of skin-centric yuzu). In Filipino cuisine you might be cutting the sour juice with water for a bracing drink. Or acid-cooking a crudo of fish. Or using it like vinegar as the souring agent in adobo, where soy sauce and sugar create a memorably delicious balance.

One of the easiest ways to make the most of the sour, aromatic citrus juice is in a pared-down, ponzu-style sauce. I detract from the authentic combination, which inludes dashi and mirin.  The spare version, which is a little more versatile (also vegan), is simple:

• 1 part  calamansi juice
• 3 parts good soy sauce or shoyu (I like to use Ohsawa nama shoyu, an organic and intensely flavorful shoyu)

Combine the strained juice with the shoyu or soy, stir well, pour into a clean bottle, and transfer to the refrigerator. It lasts indefinitely, but it is unlikely to linger unused. Use the sauce as a drizzle for exceptional raw fish, for salads, or for finishing a roasted tray of root vegetables, seafood, or grilled meats.

It is a shame to waste all that aromatic skin after juicing. The remedy is easy: salt. Pack the calamansi shells between layers of salt (I use Baleine table salt) in a jar, and keep in dark spot. The thin, fragrant skins cure quickly, becoming butter-soft and caramelized in a month. Deploy them sparingly in salads, where their flavor can sing, or use them to create foundational depth in the dishes where preserved lemons usually play.

See also:

• Baked Stuffed Apples: A Rustic Recipe Revived
• Yuzu Season Is Here: Rejoice, Harvest, and Make Yubeshi
• Cranberry Hand Pies: A Winter Necessity