Reference point
Crush a sprig of fresh dill and smell the feathery leaves.
Do this before you read on. An entry only works when you have just smelled the thing.
Sweet, green, with a clear anise note behind. Several other kitchen leaves carry an anise note — basil most clearly, and some varieties of holy basil too. But in dill that note comes with a cool green base, a combination no other leaf gives.
It is the anise note that makes dill irreplaceable. Leave it out of a fish soup and you lose a layer that no other herb can fill.
Compared with coriander, it is sweeter and less soapy. Compared with star anise, it is much lighter and greener.
How to smell it
Crush it gently rather than to a pulp — dill leaves are thin and bruise easily, which pushes the smell towards grass. Smell at once. Then smell a dried star anise, set the two side by side and decide for yourself which part sounds alike. This is an open exercise: we do not yet know which compound creates that shared note, so your notes are as valuable as ours.
Why this one is hard
Because the anise note here is so light that many people do not notice it until it is pointed out. Once noticed, it cannot be missed again — a typical way the sense of smell learns.
Don’t confuse with
This entry
Dill
Green family
Dill is sweet, with an anise note; coriander is sharp, with a soapy note. They cannot be confused side by side.
Scientific note
Most of dill oil is carvone and limonene, with a significant amount of phellandrene. The carvone here is the S form — the same isomer as in caraway seed, which is why the two sound close in the first beat although the plants are not closely related.
As for the anise note: it is real and everyone notices it, but we are not prepared to attribute it to anethole. Anethole is the dominant compound of star anise and of fennel, but in the dill studied in the literature available to us it does not appear to be present in significant amounts. The anise note here more likely comes from another compound giving a similar impression, and we leave that question open rather than guess.
In Vietnamese life
Dill is bound tightly to fish in Vietnamese cooking: grilled fish cakes, fish soup, braised fish. In the north everyone knows that when you buy fish, the fishmonger will add a handful of dill unasked — a convention nobody has ever written down.