Cilantro / Coriander Leaf
What it is
The fresh leaf and stem of Coriandrum sativum, the same plant whose dried seed is the spice coriander. Soft, lacy lower leaves (broad and flat, resembling flat-leaf parsley to the eye) give way to feathery upper foliage as the plant bolts. In British and Indian English the leaf is "coriander"; in American English, "cilantro" (from Spanish), with "coriander" reserved for the seed.
How it's made
A fast-bolting cool-season annual; it runs to seed quickly in heat, so it is succession-sown for continuous leaf. The entire plant is edible — roots included (Thai cooking pounds cilantro root into curry pastes). Drying obliterates the fresh leaf, so it is almost always sold fresh; the seed is a wholly separate dried product.
Flavor profile
To most people, a bright, fresh, citrus-and-green aroma with a soapy-cool finish — driven by aldehydes. To a significant minority, the dominant impression is pungent soap or bug-like, an aversion that is genuinely sensory, not psychological. The genetics, accurately. This trait is most strongly linked to variation near a cluster of olfactory-receptor genes, especially OR6A2, identified in a large 2012 genome-wide study; the SNP sits near genes that detect the very aldehydes that give cilantro its smell, so soap-tasters are reacting to aroma, not bitterness. It is commonly attributed to TAS2R38 in popular write-ups, but that gene governs general bitter perception (the PTC / Brussels-sprout response) and is a separate mechanism — it may contribute to some people disliking cilantro, but the famous "soap" link is olfactory (OR6A2), not bitter (TAS2R38). Worth getting right, because it changes the explanation entirely: cilantro-haters smell soap, they don't taste bitterness.
Culinary uses
Almost always added raw or at the very end — heat flattens the fresh aldehydes within a minute, leaving a faint cooked-green note. It finishes salsas, pho, Thai and Vietnamese soups, Indian dals and chutneys, and Latin American everything. The stems carry more flavor than the leaves and should be used, finely chopped, not discarded. Cilantro root, dense and savory, is pounded into Thai curry and marinade pastes and does withstand cooking. Dried cilantro leaf is effectively flavorless — there is no acceptable dried substitute. When a recipe needs cilantro and a guest is a soap-taster, culantro (long coriander), papalo, or rau răm shift the profile rather than replicate it; flat-leaf parsley gives the color and freshness but none of the citrus-aldehyde character.
Regional variations
There is little cultivar variation in the leaf itself; the variation is cultural. Mexican cooking uses it raw and in volume; Indian cooking uses both leaf (garnish, chutney) and seed (tempering, masala); Thai cooking uniquely exploits the root. "Slow-bolt" cultivars are bred for warmer climates to extend leaf harvest.
Cultural & historical context
One of the oldest cultivated herbs, with seeds found in Bronze Age sites and named in Egyptian and biblical texts. It spread along every major trade route — which is precisely why it appears as a defining fresh herb across cuisines that otherwise share nothing: Mexican, Indian, Thai, Vietnamese, Portuguese, North African, and Levantine. The soap-perception controversy has become a small culture-war of the dinner table, but it is one of the cleanest everyday examples of how a single gene shapes shared experience.
Reference notes
Suggested slug: `cilantro`. Tags: `herb`, `fresh-leaf`, `carrot-family`, `add-raw`, `genetic-aversion`, `whole-plant-edible`. Related ingredients: lime, chili, cumin, culantro, papalo, rau răm. Related cuisines: Mexican, Indian, Thai, Vietnamese, Levantine. Suggested Cuisinopedia links: Coriander Seed, Culantro, Papalo, Rau Răm, Sofrito. Flag a prominent "Why does cilantro taste like soap?" knowledge-card — high-engagement, and a natural hook for the Cuisinopedia tone. Tag the OR6A2 fact explicitly so it surfaces against the common TAS2R38 misconception.