How Thai Fermented Soybean Paste Is Made: A Visual Guide to Tao Jiew

Thai fermented soybean paste, known as tao jiew, is made by fermenting soybeans with salt brine and sometimes roasted rice or wheat flour for several months. The result is a chunky, deeply savory paste with a complex aroma that balances saltiness, earthiness, and a subtle sweetness. It is a cornerstone of Thai home cooking, lending umami and depth to dishes like jeow dipping sauces, stir-fries, and soups.

Tao jiew differs from smoother, sweeter Chinese or Japanese miso pastes; it retains visible soybean pieces and has a more pungent, salty character. In Thai kitchens, it often plays the role of a flavor enhancer rather than a main ingredient, similar to how fish sauce is used, but with a richer, fermented bean complexity.

What You Need to Make Tao Jiew

The ingredient list is remarkably short, but the quality of each component matters. Traditional tao jiew relies on just a few key items: soybeans, salt brine, and often a starchy addition like roasted rice flour or wheat flour to aid fermentation. Some recipes include a small amount of sugar or palm sugar to balance the saltiness, but the core is soybeans and salt.

• Soybeans: Dried yellow soybeans are soaked, cooked until soft, and then mashed or left whole depending on the desired texture. They provide the protein that breaks down into amino acids, creating the paste’s umami.
• Salt brine: A solution of water and salt, typically around 15–20% salt by weight. The salt draws moisture from the beans, inhibits unwanted bacteria, and encourages the growth of beneficial microorganisms that drive fermentation.
• Roasted rice or wheat flour (optional): This starchy component feeds the fermentation microbes and can add a subtle toasted aroma. It also helps bind the paste and affects the final thickness.
• Fermentation vessel: A clean glass or ceramic jar, crock, or food-grade plastic container. The vessel should be large enough to hold the bean mixture with some headspace, as gases can build up during fermentation.
• Muslin cloth or breathable cover: To cover the jar and keep out dust and insects while allowing air exchange, which is important for the aerobic stages of fermentation.

No special tools are required beyond basic cooking equipment: a pot for boiling beans, a mixing bowl, and a spoon. The real work is done by time and microbes.

The Fermentation Process Step by Step

Making tao jiew at home is a slow, patient process, but each step is straightforward. The total time from raw beans to finished paste is usually 3 to 6 months, depending on climate and desired intensity. Here is the traditional method.

1. Soak the soybeans: Rinse dried soybeans and soak them in plenty of water for at least 8 hours or overnight. The beans will double in size and soften.
2. Cook the soybeans: Drain the soaked beans and boil them in fresh water until they are completely tender and can be easily crushed between your fingers. This usually takes 1–2 hours. Drain well and let cool to room temperature.
3. Mix with flour (optional): If using roasted rice or wheat flour, toss the cooled beans with the flour until evenly coated. This step is common in Thai versions to encourage a specific fermentation culture and add a nutty note.
4. Form the bean mixture into a loose mass: Some traditional recipes pack the beans into a shallow tray or basket lined with banana leaves and let them sit in a warm, humid place for 2–3 days. This encourages the growth of mold or yeast that begins breaking down the beans. However, many home recipes skip this pre-fermentation stage and go straight to brining, which is simpler and less risky.
5. Prepare the salt brine: Dissolve salt in water. A typical ratio is 1 part salt to 4–5 parts water by weight, but ratios vary. The brine should taste very salty—like seawater, but stronger.
6. Combine beans and brine in a fermentation jar: Pack the cooked beans (and flour mixture) into the jar, then pour in enough brine to cover them by at least an inch. Weigh the beans down with a clean, food-safe weight (like a small plate or a sealed bag of water) to keep them submerged. This prevents mold growth on the surface.
7. Cover and ferment: Cover the jar with a breathable cloth secured with a string or rubber band. Place it in a warm spot, ideally around 25–30°C (77–86°F), away from direct sunlight. Stir the mixture every few days for the first couple of weeks, then less frequently. If any mold appears on the surface, remove it along with a bit of the surrounding brine.
8. Age the paste: Let the fermentation proceed for at least 3 months. The brine will gradually darken, the beans will soften and break down slightly, and the aroma will become rich and savory. The longer it ages, the deeper the flavor—some families age tao jiew for a year or more.
9. Check for readiness: The paste is ready when it has a uniform brown color, a thick but slightly chunky texture, and a salty, fermented aroma with no off-putting notes. Taste a tiny amount; it should be boldly salty and savory. If it’s too salty, it can be rinsed before use in cooking.
10. Store: Transfer the finished tao jiew to a clean jar, ensuring the beans remain covered with brine. It keeps for months at room temperature or in the refrigerator. The flavor will continue to develop slowly.

This process is forgiving; small variations in temperature, salt, and time produce different regional styles. The key is to maintain cleanliness and keep the beans submerged.

What Does Thai Fermented Soybean Paste Look, Smell, and Taste Like?

Understanding tao jiew’s sensory profile helps you use it confidently. Here’s what to expect:

• Color: Ranges from medium brown to dark chocolate brown, sometimes with a reddish tint. The brine is deep amber to almost black.
• Texture: Coarse and chunky, with visible softened soybean pieces. It is not smooth like miso; it retains a rustic, crushed-bean consistency. Some pastes are drier and crumbly, while others are wetter and more sauce-like.
• Aroma: Pungent, earthy, and distinctly fermented. It has a sharp, salty, slightly alcoholic note reminiscent of aged cheese or soy sauce, but with a beanier, more organic smell. The aroma is strong but not unpleasant—it signals deep umami.
• Taste: Intensely salty and savory (umami), with a subtle sweetness and a slight bitterness from fermentation. It is much saltier and more assertive than miso, and its flavor is more complex than plain soy sauce because of the whole bean solids.

In Thai cooking, a little goes a long way. It’s often mixed with other ingredients to create dipping sauces or used to boost the savoriness of stir-fries and soups.

How to Use Tao Jiew in Thai Cooking

Tao jiew is a versatile seasoning that adds depth without overpowering a dish when used in moderation. It appears in many classic Thai preparations:

• Jeow (dipping sauces): A common Lao and northeastern Thai condiment is jeow tao jiew, made by mashing tao jiew with garlic, chilies, lime juice, and sometimes grilled vegetables or meat. It’s served with sticky rice and raw or steamed vegetables. The paste acts as the salty, umami base.
• Stir-fries: A spoonful of tao jiew can replace or complement soy sauce in stir-fried vegetables or meats. It clings to ingredients and provides a rustic texture. For example, stir-fried morning glory or cabbage with tao jiew, garlic, and chilies is a quick, satisfying dish.
• Soups and curries: Adding a small amount to clear soups or tom yum gives a deeper savory note. In some curries, it is pounded into the curry paste for extra complexity.
• Marinades: Mixed with garlic, pepper, and a little sugar, tao jiew makes an excellent marinade for grilled meats, similar to how miso is used in Japanese cooking.
• Condiment: In its simplest form, it can be served as a side condiment with rice and fresh vegetables, much like a salty relish.

Preparation tip: Because tao jiew is chunky, it’s often mashed or pounded in a mortar with other aromatics to create a smooth paste. If the paste is too salty, rinse it briefly under water before using, or reduce the amount of other salty seasonings in the dish.

Substitutes for Tao Jiew

If you don’t have tao jiew, you can approximate its flavor and function, though the results will differ texturally and in depth. The closest substitutes are other fermented soybean pastes.

For the closest result in a Thai recipe, use a Chinese yellow bean sauce or a less spicy doubanjiang, and adjust salt and sugar. Remember that no substitute fully replicates tao jiew’s unique balance of chunkiness, salt, and fermented aroma.

Tao Jiew in Thai Cuisine: Beyond the Jar

While tao jiew is not as globally famous as fish sauce or curry pastes, it holds a special place in Thai home cooking, especially in central and northeastern regions. It is often made in small batches by families or local producers, and recipes vary from village to village. The paste is a way to preserve soybean harvests and add nutrition to simple meals. In Isan (northeastern Thailand), it is a key ingredient in jaew bong, a sweet and spicy dipping sauce that also includes dried chilies, shallots, and sometimes pork. The paste’s robust flavor stands up to the bold, fresh ingredients used in Thai salads and grilled meats.

Tao jiew also exemplifies the Thai approach to balancing flavors: salty, sweet, sour, and spicy. Its saltiness is often tempered with palm sugar and lime juice in dipping sauces, creating a condiment that is both pungent and refreshing.

Making tao jiew at home is a satisfying project that connects you to traditional preservation techniques. With just soybeans, salt, and time, you can create a complex seasoning that elevates everyday cooking.