Coriander Root Uses in Thai Cooking: Guide to Cilantro Roots

In Thai cooking, coriander roots (also called cilantro roots) are pounded into aromatic pastes, marinades and curry pastes, or simmered whole in soups and broths. They give an earthy, peppery, concentrated coriander flavor that the leaves cannot provide. The most famous use is a simple paste of coriander root, garlic and white pepper. That trio sits underneath many Thai marinades, fried dishes and soups. If you usually trim the roots off a bunch of coriander and throw them away, you are discarding one of the most valued parts of the plant in a Thai kitchen.

What Are Coriander Roots and Why Do Thai Cooks Value Them?

Coriander roots are the pale taproots at the base of a coriander (cilantro) plant, the part below where the green stems begin. In Thai they are called rak phak chi. Thai cooks prize them because the root holds a deeper, earthier and more intense version of coriander's aroma. That flavor also stands up better to pounding, frying and long simmering than the delicate leaves do.

A useful way to picture the plant is from top to bottom. The leaves are bright and fresh, and they are usually added at the end. The stems are juicy and green-tasting. The roots are the most robust part, so they work at the start of cooking, where flavors are built rather than finished.

How to Recognize Coriander Roots

A coriander root is a thin, tapering taproot, usually a few centimeters long. It ranges in color from off-white to pale beige. The top, where it joins the stems, can sometimes show a faint pink or purplish tinge. The main root often has fine, hair-like rootlets and may carry soil trapped between them. It feels firm and slightly fibrous, not soft or juicy like the stems.

To check what you have, scratch or crush a root between your fingers. Coriander root smells clearly of coriander, but warmer and earthier, with a slight peppery edge. Parsley root, which can look similar, smells of parsley and celery instead.

Many supermarkets sell coriander with the roots cut off. Asian grocers and farmers' markets are more likely to sell whole bunches with roots attached. Growing your own coriander is another reliable source, because the whole plant comes out of the soil.

How Coriander Roots Differ from Similar Items

Item	Appearance	Aroma and flavor	Typical use in Thai cooking
Coriander root	Thin, pale beige taproot with fine hairs; firm and fibrous	Earthy, deep, slightly peppery coriander	Pounded pastes, marinades, curry pastes, simmered broths
Coriander stems	Slim green stalks, tender and juicy	Fresh, green, milder than root	Chopped into salads, sauces, sometimes pastes
Coriander leaves	Flat, lacy, bright green	Bright, fresh, citrusy-herbal	Garnish and finishing herb
Coriander seeds	Small, round, tan husks	Warm, citrusy, floral; quite different from fresh coriander	Toasted and ground in some curry pastes
Parsley root	Much larger, cream-colored, like a slim parsnip	Parsley and celery; no coriander scent	Not a Thai ingredient

The Thai Flavor Base: Coriander Root, Garlic and White Pepper

The most important coriander root use in Thai cooking is a three-ingredient paste. It combines coriander root, garlic and white pepper, pounded together. In Thai kitchens this combination is often nicknamed saam gler, roughly "the three friends". It works as an all-purpose aromatic base, in the way some cuisines start with onion, celery and carrot.

Each ingredient contributes something different:

Coriander root adds earthy, herbal depth and a lasting coriander aroma that survives heat.
Garlic adds pungency and savory sweetness, especially once it is fried.
White pepper adds a sharp, warming heat with a musky aroma. Thai cooks generally prefer it to black pepper in this paste. It tastes cleaner and less fruity, and it does not leave dark specks.

A common starting point is about 2 coriander roots, 3 to 4 garlic cloves and roughly half a teaspoon of white peppercorns. Treat this as a guide rather than a fixed rule. Thai recipes vary widely, and cooks adjust the balance to taste and to the dish.

Main Cilantro Root Uses in Thai Dishes

Cilantro roots appear in Thai cooking in five main ways. They go into marinades for grilled and fried meat, curry pastes, soups and broths, dipping sauces, and stir-fried or deep-fried garlic-pepper dishes.

Marinades for Grilled Meats

The coriander root, garlic and white pepper paste is a classic base for marinating meat before grilling. It is typically mixed with seasonings such as fish sauce, soy sauce, oyster sauce or palm sugar. Familiar examples include Thai grilled chicken (gai yang) and grilled pork skewers (moo ping). Recipes for both often build on this trio. On the grill, the paste forms a fragrant, lightly charred coating, and the pale root fibers almost disappear into the surface.

Curry Pastes

Coriander root is a standard component of many Thai curry pastes, including green curry paste. It is pounded with ingredients such as chilies, lemongrass, galangal, shallots, garlic and shrimp paste. In a curry paste, coriander root adds a green, earthy layer underneath the brighter citrus notes of lemongrass and kaffir lime. Because the root is fibrous, it is usually sliced finely before pounding so it breaks down into a smooth paste.

Soups and Broths

Whole or lightly bruised coriander roots are simmered in Thai stocks and clear soups to perfume the broth. Examples include the mild clear soup gaeng jued and rice soups. Simply crush each root with the flat side of a knife or a cleaver and drop it into the pot. The roots release their aroma slowly and can be lifted out or left in. This is one of the easiest ways to use leftover roots, because it needs no pounding at all.

Dipping Sauces

Some Thai dipping sauces, particularly the sour, garlicky and spicy sauces served with seafood, include pounded coriander root alongside chilies, garlic, lime juice and fish sauce. Here the root is used raw. It gives a fresher, sharper herbal note than it does when cooked.

Garlic and Pepper Fried Dishes

Dishes such as pork fried with garlic and pepper (moo tod kratiem prik thai) rely on the same trio. The paste coats the meat and is fried until golden. The coriander root keeps the garlic and pepper from tasting flat and one-dimensional.

How to Clean and Prepare Coriander Roots

Coriander roots need careful cleaning because soil collects between their fine hairs and at the crown where the stems meet. Follow these steps:

Cut the root off the bunch just below where the green stems begin. You can include a little of the pale lower stem.
Soak the roots in a bowl of cold water for a few minutes to loosen the soil.
Scrub each root gently with your fingers or a soft brush, paying attention to the crown.
Rinse under running water and check that no grit remains.
Trim off any very thin, stringy tips and any dried or discolored parts.
Slice the roots finely across the grain if you will pound them. Leave them whole and crush them lightly if they are going into a broth.

Pounding Coriander Roots with a Mortar and Pestle

A mortar and pestle is the traditional Thai tool for turning coriander roots into paste. Pounding crushes the fibers and releases the aromatic oils more fully than chopping. Thai kitchens commonly use a heavy granite mortar for pastes. Taller clay or wooden mortars are associated more with pounded salads such as green papaya salad.

Start with the hardest, driest ingredient. For the basic paste, crush the white peppercorns first.
Add the sliced coriander roots and pound until they break into a coarse, fibrous mash.
Add the garlic and continue pounding until everything forms a fairly smooth, fragrant paste.
Use the paste right away for the best aroma, or store it as described below.

A small food processor or blender can be used instead, but it has limits. Small quantities tend to spin around the blade rather than break down. Blades cut fibrous roots rather than crushing them, so the texture is often less smooth. Many cooks find the aroma of pounded paste more pronounced. If you do not have a mortar, chopping the ingredients very finely and then pressing them with the flat side of a knife gets you closer to a pounded texture.

How to Store Leftover Coriander Roots

Coriander roots keep better than the leaves, which makes them a practical leftover to save. Store them in one of these ways:

Refrigerator: Keep cleaned, dried roots wrapped in a paper towel inside a container or bag. Use them within several days, while they are still firm.
Freezer, whole: Freeze cleaned, dried roots in a sealed bag. Frozen roots are softer once thawed, but they work well in pastes and broths.
Freezer, as paste: Pound the coriander root, garlic and white pepper paste and freeze it in small portions, such as in an ice cube tray. You can then take out a portion for a marinade or stir-fry.

Collecting roots in the freezer each time you buy a bunch of coriander is a simple way to build up enough for a batch of paste.

Substitutes for Coriander Roots and Their Limitations

The closest substitute for coriander root is the thick lower part of the coriander stems. No substitute fully matches the root's earthy depth. Stems are the most practical option when you cannot find whole bunches.

Substitute	How to use it	Limitations
Lower coriander stems	Use a larger amount than the root, chopped finely and pounded	Greener and milder; less earthy; more moisture in the paste
Stems plus a few leaves	Pound together to boost the coriander aroma	Leaves add brightness rather than depth and can darken pastes
Frozen coriander roots	Use straight from frozen in pastes and broths	Softer texture; best in cooked dishes rather than raw sauces
Ground coriander seed	A small pinch only, in cooked dishes	Tastes warm and citrusy, not like fresh coriander; a different flavor, not a true replacement

If you are using stems instead of roots in the garlic and white pepper paste, the result will still be good. It will simply taste fresher and lighter than the original.

Getting Started with Coriander Roots

The easiest first step is to save the roots from your next bunch of coriander. Clean them, crush them and drop them into a pot of chicken or vegetable broth. When you are ready for more, pound them with garlic and white pepper. Then use that paste to marinate chicken or pork before grilling or frying. These two uses show what coriander roots contribute to Thai food: a deep, earthy aroma built in from the start, rather than sprinkled on at the end.