Sesame Seeds

The hull has to break for the flavour to come out

A sesame seed keeps its aroma and its oil inside a hard hull. A seed swallowed whole passes through giving up almost none of either.

Which is why Korean cooking does not simply scatter sesame — it uses kkaesogeum, toasted seeds lightly crushed in a mortar and mixed with salt. That is what makes whole and crushed seeds two different ingredients, and why sprinkling whole seeds over a dressed vegetable dish tastes flatter.

• Whole — texture and a visual finish. The scattering over bibimbap.
• Crushed — for aroma. The seasoning in dishes like sigeumchi-namul and kongnamul-muchim.

Even crushing them between your palms as you add them beats whole.

Toasting is half of it

Raw sesame has very little smell. In a dry pan over medium-low heat, three to five minutes, shaking constantly, until a few seeds jump and it smells nutty.

• No oil. The seeds have plenty of their own.
• Take them out before they darken. They keep cooking on residual heat, so tip them straight onto a plate.
• Burnt sesame is bitter and there is no fixing it.

Even seeds sold pre-toasted lift noticeably from a brief re-toast at home (blooming spices).

Not the same thing as sesame oil

Sesame oil is pressed from toasted seeds, so the aroma points the same way, but it does a different job: the oil is liquid fat and the seeds are a solid ingredient. They do not substitute for each other — seeds swapped for oil lose the texture, oil swapped for seeds loses the fat.

What they share is that heat destroys the aroma of both, so both go in at the end.

White and black

• White — mild and nutty. The default for Korean dressings and seasonings.
• Black — stronger, slightly bitter, with a thicker hull that needs more decisive crushing. Used in desserts and in songpyeon filling.

Interchangeable by weight, but black is visually loud, so in a pale dish it should be a decision.

Elsewhere it is used as a paste

Tahini is sesame ground to a paste, and it is the note underneath hummus and baba ganoush. Whole seeds cannot stand in for it — it has to be ground and emulsified to blend into a sauce at all (emulsions).

Japanese goma-dare is built on crushed sesame in the same way.

Storing — it goes rancid quickly

Sesame is over 50% oil, so it spoils considerably faster than other dry store ingredients.

• Untoasted: six months refrigerated, a year frozen. Do not leave it out for long.
• Toasted seeds lose aroma over time, so toast what you need rather than a big batch.
• Judge by smell: when the nuttiness is gone and it smells faintly of paint, it is rancid. If it tastes bitter you are already past it.
• Kkaesogeum draws moisture through its salt, so keep it sealed and refrigerated and use it within two or three weeks.