Identify fingerroot or krachai and choose a form for Thai cooking

What krachai is

Krachai, also written kra chai, is the Thai name for fingerroot, a member of the ginger family. Its botanical name is Boesenbergia rotunda; older references also call it Boesenbergia pandurata. The part used in cooking is the rhizome, the underground stem that sends out the plant's roots and shoots. Krachai has its own place in Thai cooking. It is not another name for ginger or galangal, and recipes that call for it usually expect fingerroot itself.

How to recognize fingerroot and its names

The English name describes the rhizome: krachai grows as a cluster of slender, finger-shaped pieces. That shape is the quickest way to tell it apart from ginger and galangal, which both grow as broader, knobbier rhizomes.

• Krachai or kra chai: the Thai name, used in recipes and on imported packaging.
• Fingerroot or finger root: the common English name. Some labels and ingredient guides call it finger root ginger, which reflects the family it belongs to rather than suggesting it can replace ginger.
• Chinese keys: another English name listed in specialist spice references.
• Boesenbergia rotunda or Boesenbergia pandurata: botanical names, useful when a package or seller lists a scientific name.

Watch for one naming mix-up. Gernot Katzer's spice reference warns that kencur, the name of a different rhizome, is sometimes wrongly applied to fingerroot. If a product is labeled kencur, don't assume it is krachai. Check for one of the names above or a Boesenbergia botanical name instead.

Krachai vs. galangal

Galangal and krachai are separate ingredients, and some Thai recipes call for both. Thai Cooking Koh Tao, a cooking school, lists fingerroot and galangal as separate items in its curry pastes. If a recipe names both, buy both. One does not stand in for the other.

Where krachai is used in Thai cooking

In the kitchen guide by Thai cook Suwanee of Simply Suwanee, krachai is tied to nam ya, jungle curry, pad cha and gaeng som. If you are looking for a recipe that uses krachai, those dish names are good search terms. Katzer's reference describes fresh fingerroot being grated or thinly sliced, and dried pieces being soaked before grinding.

Where to buy it and what forms you will find

When you shop, look for any of the names above, and expect several forms. Suwanee's guide describes krachai sold fresh, frozen, whole in brine, shredded in brine and powdered. Powdered fingerroot is also sold as a packaged spice. Read the label for the name, botanical name if given, form and any brine ingredients, so you know which preparation the product needs.

Choosing a form for your recipe

Form	How it is prepared	Notes
Fresh	Grated or thinly sliced, as Katzer's reference describes	The form most recipes for fresh krachai assume
Frozen	Listed by Suwanee as a form she uses	A fingerroot form, not a different ingredient
Whole in brine	Suwanee soaks brined krachai to reduce saltiness and discards the brine	Account for added salt and check the label's brine ingredients
Shredded in brine	Same soaking approach, with the brine discarded	Already cut, so it skips slicing or grating
Dried or powdered	Katzer describes soaking dried pieces before grinding; powder is already ground	Best with recipes written for a dried or powdered form

Fresh, frozen, brined and powdered fingerroot do not have a standard conversion between them. The most reliable approach is to use a recipe written for the form you have, rather than guessing how much powder replaces a fresh amount.

Substitutes for krachai

The best stand-in for krachai is another form of krachai. Suwanee's advice is to switch to a different fingerroot form, such as brined or powdered when fresh is unavailable, rather than assuming ginger or galangal will reproduce its flavor. Neither of them comes with a reliable swap ratio.

Leaving it out is sometimes an option, but only when the recipe allows it. Thai Cooking Koh Tao marks fingerroot as optional in some of its curry-paste recipes. That is a choice made for those recipes, not a general rule. Where krachai is central to a dish, getting some form of it is the better choice.

Example: a shopping worksheet

This illustrative worksheet helps you match what the recipe asks for with what you can actually buy. Fill in one line per item before shopping, then compare it with the package in your hand.

Requested name:     krachai / fingerroot
Botanical name:     Boesenbergia rotunda (if listed)
Form in recipe:     fresh
Form available:     shredded in brine
Brine ingredients:  (copy from label)
Recipe quantity:    (from recipe)
Preparation:        soak to reduce salt, discard brine
Form mismatch?      yes -> find a recipe written for brined krachai

If the form you can find differs from the one in your recipe, choose a recipe written for that form instead of inventing a conversion.