What Is Grass Jelly? Plant Source, Ingredients and How It's Made

Grass jelly is a dark, almost black, gently bitter jelly made from the dried leaves and stems of the grass jelly plant, Mesona, a herb in the mint family. The dried plant is boiled for a long time to draw out its juices. The liquid is then filtered, thickened with starch and left to cool until it sets. In Thailand it is called chao kuai (เฉาก๊วย). It is usually cut into cubes and served over crushed ice with a dark brown sugar syrup, which makes it a cooling street dessert and drink topping.

What is grass jelly?

Grass jelly is a plant-based jelly with a herbal flavor. It does not contain gelatin, and despite its name it is not made from lawn grass. The "grass" refers to the leafy herb used to make it. The Thai name chao kuai comes from Teochew Chinese, which reflects the jelly's roots in southern Chinese cooking. It became part of Thai food through Thai-Chinese communities. The same food is known as xian cao in Mandarin and cincau in Malaysia and Indonesia.

How to recognize grass jelly

Color: deep brown to jet black. Thin slices held up to light show a faint amber or greenish-brown glow at the edges.
Shape: it is sold as a large block, in tubs or cans, and in markets it is cut into cubes, rectangles or thin strips.
Surface: glossy and wet-looking, often with a thin film of liquid around it.
Texture: soft and wobbly. It is more tender and less springy than gelatin jelly and breaks cleanly when pressed with a spoon.
Aroma and taste: mildly herbal, slightly woody or smoky, with a light bitterness that some people compare to weak tea. On its own it is barely sweet, so the syrup supplies most of the sweetness.

What plant is grass jelly made from?

Grass jelly is made from Mesona, often called Chinese mesona or the grass jelly plant. Botanists now classify it as Platostoma palustre, and the older name Mesona chinensis is still common on packaging. It is a small, soft-stemmed herb in the mint family (Lamiaceae) and grows in southern China and Southeast Asia.

The fresh plant looks like an ordinary leafy green herb. It only becomes useful for jelly after drying. Producers harvest the stems and leaves and dry them in the sun. Some also store them for a period so the color darkens. The dried bundles are brown to black, brittle and smell earthy and tea-like. This drying stage helps create the deep color and smoky-herbal flavor of black grass jelly. The plant also contains natural gum-like substances, and these help the jelly set once starch is added.

Grass jelly ingredients

The main grass jelly ingredient is the dried Mesona plant. A basic grass jelly needs only a few more items: water, a starch and sometimes a small amount of alkali. Sugar is usually added at serving time rather than cooked into the jelly.

Ingredient	What it looks like	What it contributes
Dried grass jelly plant (Mesona)	Brittle dark brown leaves and stems	Color, herbal-bitter flavor, aroma and natural gelling substances
Water	—	Draws the flavor and gum-like compounds out of the plant during long boiling
Starch (tapioca, rice, corn or potato starch)	Fine white powder	Thickens the dark liquid and works with the plant's gums to make a firm, sliceable jelly
Alkali (for example, potassium carbonate, often sold as lye water, or baking soda), used by some producers	Clear liquid or white powder, used in small amounts	Helps extract the plant's compounds and supports a firmer set and darker color
Sugar or syrup (at serving)	Brown sugar syrup, palm sugar syrup or white sugar	Sweetness that balances the jelly's bitterness

Commercial grass jelly sold in cans or tubs may also list preservatives or extra thickeners. The ingredient label shows exactly what a particular product contains.

How is grass jelly made?

Grass jelly is made in three main stages: plant extraction, filtering and gelling. The dried plant is boiled to make a dark liquid, the liquid is strained, and then it is thickened with starch and cooled until it sets.

Dry the plant. Harvested Mesona stems and leaves are dried until brittle. This gives the plant its dark color and concentrated flavor.
Rinse and boil. The dried plant is rinsed, then simmered in a large pot of water for a long time. Some producers add a little alkali at this stage. As the plant cooks, the water turns into a thick, inky brown-black liquid with a tea-like, woody smell. This step is the plant extraction.
Filter the liquid. The cooked plant matter is strained out through a fine sieve, cloth or press. What remains is a smooth, dark, slightly slippery extract. Filtering removes fibers and grit so the finished jelly is clean and even.
Add starch. Starch is mixed with a little cool water to make a slurry. It is then stirred into the hot extract. Stirring constantly prevents lumps and stops the mixture from catching on the bottom of the pot.
Cook until thickened. The mixture is heated and stirred until it turns glossy and noticeably thicker, like a loose pudding. This is the gelling stage, where the starch and the plant's natural gums begin to bind.
Pour and set. The hot mixture is poured into trays, molds or containers and left to cool. As it cools, it firms into a dark, wobbly block.
Cut and serve. Once fully set, the block is turned out and cut into cubes or strips for desserts and drinks.

Traditional and commercial grass jelly production

In traditional grass jelly production, the plant is boiled and strained in large pots by hand. In commercial grass jelly production, the same basic steps are carried out at larger scale. Factories make grass jelly in tubs and cans for markets and dessert shops. Some factories also dry the extract into a powder that is pre-mixed with starch, which home cooks can buy. The principle stays the same: a dark plant extract plus starch, cooked and cooled until it gels.

How to make grass jelly at home from powder

Home cooks rarely boil the dried plant. Grass jelly powder, a dried extract usually blended with starch, is much easier to find in Asian grocery stores. The water amount and cooking time differ between brands, so follow the package directions.

Whisk the powder into the amount of cool water stated on the package until no dry lumps remain.
Pour the mixture into a pot and heat it over medium heat, stirring constantly with a spatula or wooden spoon.
Keep stirring until the liquid boils and turns thick and glossy.
Pour it into a heat-safe dish or container and let it cool to room temperature.
Refrigerate until firm, then cut it into cubes with a knife dipped in water.

Tip: Stir right down to the bottom of the pot. The mixture thickens quickly and can scorch, and scorching leaves a burnt taste.

How grass jelly is served in Thailand

In Thailand, grass jelly is mostly eaten as a sweet, cooling snack. Its mild bitterness and soft texture contrast well with sweet syrup and icy cold. Common ways to enjoy chao kuai include:

With brown sugar syrup and ice: the classic version. Cubes of jelly are placed in a bowl or glass, covered with crushed ice and drizzled with dark, caramel-scented brown sugar syrup.
With fresh milk: jelly cubes in cold milk, sometimes with syrup. The milk softens the bitterness and creates a striking black-and-white look.
In drinks: as a topping in milk tea, iced coffee or bubble tea, where it adds a soft, slippery bite.
In mixed iced desserts: alongside other toppings in shaved-ice bowls.

Street vendors often keep a large block of grass jelly in a tray and cut portions to order. The shiny black cubes are easy to spot next to the brighter jellies and beans on a dessert cart.

How grass jelly differs from similar jellies

Grass jelly is easy to confuse with other dark or translucent Asian jellies. Its plant source, color and flavor tell them apart.

Jelly	Made from	Color and texture	Flavor
Black grass jelly (chao kuai)	Dried Mesona plant extract and starch	Brown-black, glossy, soft and wobbly	Mildly bitter, herbal, woody
Green grass jelly (cincau hijau)	Fresh leaves of a different plant, squeezed in water	Bright to deep green, very soft	Fresh, leafy, grassy
Herbal jelly (guilinggao)	A blend of Chinese medicinal herbs	Very dark, dense	Noticeably more bitter and medicinal
Coffee jelly	Coffee set with gelatin or agar	Dark brown, firmer, more springy	Coffee bitterness, no herbal note
Aiyu jelly	Gel from the seeds of a type of fig	Pale yellow to clear, delicate	Very mild, usually served with lemon

Substitutes for grass jelly and their limitations

No substitute fully copies grass jelly, because its flavor comes from the Mesona plant. These options can stand in when you need a similar look or role in a dessert:

Canned grass jelly: the closest choice. It is ready to cut and use, but it is often softer and may taste slightly of the can or of preservatives.
Coffee jelly: similar dark color and gentle bitterness. However, it tastes clearly of coffee, contains caffeine and is usually firmer.
Agar jelly made with strong black tea: gives a dark, slightly bitter jelly. Agar sets firmer and more brittle, and the flavor is tea rather than herbal.
Plain agar or gelatin cubes: provide the jelly texture in drinks but none of the color or herbal taste.

Homemade grass jelly is best kept covered in the refrigerator and eaten within a few days. Over time the block may release a little liquid, and its texture becomes less smooth.