Korean Soy Sauce (Ganjang): How to Make & Use It

Korean soy sauce, known as ganjang, is a cornerstone of Korean cooking, made from fermented soybeans, wheat, and brine. Unlike Japanese or Chinese soy sauces, Korean ganjang has a distinct, deeply savory flavor with a slightly sweet and nutty undertone, often used in marinades, soups, and dipping sauces. This recipe guides you through making a traditional, homemade ganjang that develops complex umami over time, and it also covers how to use it in everyday dishes.

Ingredients

10 cups (2.4 L) filtered water
3 cups (600 g) Korean soybeans (or any dried soybeans)
1 cup (240 g) coarse sea salt (non-iodized)
1 piece (about 4 inches / 10 cm) dried kelp (dashima or kombu)
1 small onion, halved (optional)
5-6 dried shiitake mushrooms (optional)

Instructions

Soak the soybeans: Rinse the soybeans and soak them in plenty of water for 8-12 hours or overnight. Drain and rinse again.
Boil the soybeans: Place the soaked beans in a large pot, cover with fresh water (about 2 inches above the beans), and bring to a boil. Reduce heat to medium-low and simmer for 1.5 to 2 hours, until the beans are very soft and easily mashed. Drain, reserving the cooking liquid.
Mash the beans: Mash the cooked beans with a potato masher or in a food processor until they form a thick paste. You can leave some texture if you like.
Shape and dry: While the bean paste is still warm, shape it into a firm brick or ball (about 6 inches in diameter). Place it on a clean, dry surface (like a bamboo mat or a wooden board) in a cool, dry, well-ventilated area. Let it dry for 2-3 days, turning occasionally, until the surface is hard and no longer sticky.
Ferment the brick: Once dried, place the brick in a large, clean, dry jar or crock. Cover the jar with a breathable cloth (like cheesecloth) and secure with a string. Store in a cool, dark place (60-70Â°F / 15-21Â°C) for 3-6 months. This is the meju fermentation stage, where beneficial mold and enzymes develop. Check periodically for any off-odors or excessive moisture; discard if it smells rotten or shows black or pink mold.
Make the brine: After the fermentation period, bring the 10 cups of water to a boil. Add the sea salt and stir until fully dissolved. Let the brine cool completely to room temperature.
Combine and age: Place the fermented meju brick, kelp, onion, and shiitake mushrooms (if using) into a large glass jar or ceramic crock. Pour the cooled brine over the brick, making sure it is fully submerged. Cover the jar with a breathable cloth and secure it.
Age the sauce: Store the jar in a cool, dark place for at least 6 months, preferably 1 year. During the first month, stir the mixture every few days to help the flavors develop. After the first month, you can leave it undisturbed. The longer it ages, the deeper the flavor.
Strain and bottle: After aging, strain the liquid through a fine-mesh sieve lined with cheesecloth. Discard the solids. Transfer the ganjang to sterilized bottles or jars. The remaining solid paste can be used as a seasoning paste (doenjang-like) or discarded.

Tips

Substitutions: If you can’t find Korean soybeans, use any dried soybeans. For a gluten-free version, you can omit the wheat (though traditional ganjang uses wheat, most commercial versions do too; this recipe is naturally gluten-free if you skip the wheat, which is not used in this recipe).
Storage: Homemade ganjang is not pasteurized, so it must be stored in the refrigerator after bottling. It will keep for up to 1 year refrigerated. For longer storage, you can freeze it in ice cube trays.
Common Mistake: The biggest mistake is not letting the meju dry thoroughly before fermentation, which can cause unwanted mold. Also, do not use iodized salt, as it can inhibit fermentation and give a bitter taste.
Flavor adjustment: If your ganjang is too salty after aging, you can dilute it with a little water when cooking. If it’s not salty enough, add a pinch of salt to taste.

Serving Suggestions

Use your homemade ganjang as a dipping sauce for dumplings (mandu), as a seasoning for Korean soups (like doenjang jjigae or seawood soup), or as a marinade for beef or chicken (bulgogi). It also works beautifully as a simple table condiment mixed with a little vinegar and sesame oil for dipping fresh vegetables.

Variations

Yangjo Ganjang (Light Soy Sauce): This is the first, lighter extraction from the meju, made by pouring brine over a fresh meju. It’s lighter in color and more delicate in flavor, used for soups and clear dishes.
Jin Ganjang (Dark Soy Sauce): This is a second extraction, where the same meju is re-brined after the first extraction, resulting in a darker, saltier sauce used for braising and coloring.
Seasoned Ganjang: Add a few whole dried red chilies, a clove of garlic, and a slice of ginger to the aging jar for a subtly spiced version.

Storage and Reheating

Store the bottled ganjang in the refrigerator; it will keep for up to 1 year. There is no reheating needed for soy sauce; it is used cold or at room temperature. If you freeze it, thaw in the refrigerator before use.

Frequently Asked Questions

Can I make Korean soy sauce without the long fermentation? No, the fermentation is essential for developing the characteristic umami and flavor. You can use a shortcut by mixing store-bought soy sauce with a bit of miso paste, but it won’t be the same.

What if my meju develops green or white mold? A little white or green mold on the surface is normal and part of the fermentation. However, if you see black or pink mold, or if it smells foul, discard the batch and start over.

Is it safe to eat the fermented soybeans? Yes, after fermentation, the soybeans are safe to eat. The paste left after straining can be used like doenjang (soybean paste), though it will be saltier and less fermented.

Can I use regular table salt instead of sea salt? It’s best to use non-iodized salt, as iodine can inhibit fermentation and cause off-flavors. Coarse sea salt is ideal.

Why is my ganjang cloudy? Cloudiness is normal for homemade ganjang and is due to natural sediment. You can filter it again if you prefer a clearer sauce, but it’s harmless.

How long does homemade ganjang last? Properly refrigerated, it lasts up to 1 year. Always use a clean, dry spoon to avoid introducing bacteria.

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Safety notes: safe minimum internal temperatures from USDA FSIS; raw and undercooked fish guidance from the U.S. FDA. Food safety notes

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