Grass jelly is made by boiling the aged and slightly oxidized stalks and leaves of Mesona chinensis (member of the mint family) with potassium carbonate for several hours with a little starch and then cooling the liquid to a jelly-like consistency. This jelly can be cut into cubes or other forms, and then mixed with syrup to produce a drink or dessert thought to have cooling (yin) properties, which makes it typically consumed during hot weather. The jelly itself has a slight bitter taste, a light iodine lavender flavor, and is a translucent black. It can also be mixed with soy milk to produce a milky white liquid with black strands in it.

In China, grass jelly was traditionally served with sugar syrup. Now it is often served mixed with other ingredients, such as mango, sago, watermelon, cantaloupe, and other fresh or canned fruit, and evaporated milk.

Although this dish is sometimes called liangfen in Chinese, it should not be confused with the Chinese starch jelly liangfen, which is an entirely different dish.