Ingredient

Lemongrass

Lemongrass is a tough, fibrous grass with a clean citrus aroma that lemon itself does not have. It has to be handled in one of two ways — bruised whole and removed, or sliced extremely thin — because anything in between leaves woody splinters in the finished dish.

Why the two methods

Lemongrass is structurally a grass: long parallel fibres running the length of the stalk, tough enough to be genuinely unpleasant to eat. The aroma, largely citral, sits in the tender inner layers of the lower stalk.

Bruising a whole stalk cracks those fibres enough to release the aroma into a liquid while leaving the stalk intact to be lifted out. This is what a curry, a soup or an infusion wants.

Slicing it very thin — a millimetre or less, across the fibres — breaks them into pieces short enough to eat. This is what a salad, a paste or a stir-fry wants. A coarse chop gives you the worst of both: splinters that are neither removable nor edible.

Preparing a stalk

1. Cut off the dry, papery top two thirds. It has little aroma and is entirely woody. Keep it for a stock or a tea.
2. Trim the root end and peel away the tough outer layers until you reach the paler, softer core.
3. For an infusion: bash the stalk along its length with the back of a knife or a rolling pin until it splits and smells strongly. Add it whole, and remove it before serving.
4. For eating: slice the tender lower section across the fibres as thinly as you possibly can, then chop the slices finely.
5. For a curry paste: slice thin first, then pound or blitz. Whole pieces never break down properly.
6. Freeze surplus stalks whole. They keep for months and are easier to slice thinly from frozen.

Buying, keeping and substituting

What to look for

Firm, plump, pale at the base and green above. Dry, shrivelled, grey stalks have lost most of their aroma.

Keeping

A week or two in the fridge wrapped loosely; several months in the freezer.

Dried and powdered

Weak and papery. Better than nothing in a paste, and no substitute in an infusion.

Lemongrass paste in a tube

Convenient and usually contains a good deal else. Acceptable in a curry, poor where the aroma is the point.

Substitutes

Lemon zest and a little makrut lime leaf together come closest. Lemon juice does not — the aroma is in peel oils and grass, not in acid.

What to use it in

• Thai and Malaysian curry pastes, sliced thin and pounded with galangal, garlic, chilli and shrimp paste.
• Tom yum and tom kha, bruised whole with galangal and makrut lime leaves, and lifted out before eating.
• Vietnamese marinades for grilled pork or beef, sliced very fine.
• A steaming liquid for fish, bruised, with ginger and spring onion.
• In a broth or a poaching liquid for chicken.
• In a cordial or syrup, with lime and ginger, which is excellent and underused.
• As a skewer, using the woody upper stalk, for prawns or pork.

Common questions