Reference point
Crush a serrated culantro leaf and smell it at once.
Do this before you read on. An entry only works when you have just smelled the thing.
Sharply green, pungent, with a metallic note and a little damp. Many times stronger than ordinary coriander.
Culantro and coriander share the same group of aldehydes that give their characteristic pungency, but culantro is far more concentrated. That is why a single culantro leaf is enough for a whole bowl of pho, while coriander takes a handful.
This group of aldehydes is also what makes a significant share of people find coriander soapy — a difference with a genetic basis, not a matter of taste.
How to smell it
Crush a culantro leaf in one hand and a sprig of coriander in the other, and smell them in turn. What they share is the aldehydic pungency; what differs is the intensity and a damp layer only culantro has.
Why this one is hard
Because it is usually thought of as a strong version of coriander rather than a smell of its own. Smell it on its own for long enough and you will find a damp layer that coriander lacks entirely.
Don’t confuse with
This entry
Culantro
Green family
The same group of aldehydes, but culantro is many times stronger and has a damp layer that coriander lacks.
Scientific note
Culantro contains E-2-dodecenal, a twelve-carbon aldehyde with an extra double bond. That unsaturated form is the signature compound of culantro, and its detection threshold is very low.
Coriander also contains similar straight-chain aldehydes, so the two herbs do not differ in whether they have this group of compounds. The difference is concentration and the unsaturated form — which is why one culantro leaf is enough for a bowl of pho while coriander takes a handful, and also why culantro stands up to heat for longer.
In Vietnamese life
Culantro is also a familiar herb in the Caribbean and Latin America. In Vietnam it is an essential herb for pho and many sour soups.