Cold sauces & condiments
Ganjang
간장 · Ganjang is the Korean family of fermented liquid soy condiments, made traditionally by aging meju (fermented soybean blocks) in salt brine inside onggi (Korean earthenware) pots under the sun. It serves as the savory, umami backbone of Korean cuisine, distinct from Chinese and Japanese soy sauces in its saltier profile, lighter color in its traditional form, and primarily soybean-only fermentation.
The formula
4 kg dry soybeans : 13 L water : 2.5 kg sea salt
Traditional guk-ganjang ratio; yields roughly 10 L of finished soy sauce after months of fermentation
Identity
- Korean
- fermented
- soy-based
- umami-rich
- traditional jang
- salt-cured
Ingredients
| Base | fermented soybean blocks (meju) | Boiled, molded, and koji-inoculated soybeans; the flavor foundation |
| Liquid | water | Clean, traditionally unchlorinated water for the brine |
| Seasoning | sea salt or rock salt | Roughly 20% concentration prevents spoilage and drives osmotic extraction |
| Culture | wild Aspergillus (nuruk/koji) from rice straw | Inoculated naturally onto meju during sun-drying; converts proteins into umami-rich amino acids |
| Enrichment | wheat (optional) | Used in yangjo-ganjang variants for a slightly sweeter, mellower profile; absent from pure guk-ganjang |
Method
- 1Soak and boil soybeans, then mash and shape into brick-like blocks called mejuBoiling gelatinizes starches and denatures proteins, creating the substrate that koji mold will colonize
- 2Sun-dry and air-ferment the meju blocks for 2–4 weeks, often tied with rice strawRice straw carries wild Aspergillus and Bacillus; drying concentrates the bean while allowing enzymes to break proteins into umami precursors
- 3Prepare brine by dissolving sea salt in water at roughly 20% concentrationHigh salinity suppresses spoilage bacteria while permitting salt-tolerant fermentation
- 4Submerge aged meju in the brine inside an onggi (unglazed earthenware) jar, weigh down, and leave outdoorsOnggi's microporous clay allows slow gas exchange; sun-warmed days and cool nights drive long, complex fermentation
- 5After 3–6 months (traditionally through winter and spring), drain the dark amber liquid — this is guk-ganjangThe first extraction captures the most concentrated, salt-balanced soy sauce; the residual meju at this stage becomes doenjang
- 6Optionally refill the pot with fresh brine for a second, lighter extraction yielding jin-ganjangReusing the spent meju with new brine produces a milder, darker sauce suited to dipping and color-driven dishes
Techniques that matter
Meju fermentation
Builds the enzymatic and microbial complexity that defines Korean jang
Onggi aging
Earthenware porosity supports slow oxidative aging impossible in sealed vessels
Solar temperature cycling
Diurnal warmth and cool nights extend fermentation and deepen umami
Variations & derivatives
Guk-ganjang (국간장)Korea (traditional)
Soup soy sauce; pure soybean and salt; light color, intensely salty and savory; also called Joseon-ganjang
Yangjo-ganjang (양조간장)Korea (modern brewed style)
Uses wheat and sometimes a koji starter; mellower and slightly sweet
Jin-ganjang (진간장)Korea (Chinese/Japanese influence)
Darker and sweeter; often a second extraction or commercial style; well suited to dipping sauces
Used in these dishes
Substitutions
- guk-ganjang → fish sauce — Maangchi's preferred substitute; provides comparable salinity and umami, though the flavor profile differs
- guk-ganjang → Chinese or Japanese light soy sauce — Closer in color but far less salty and lacking guk-ganjang's depth; not robust enough to flavor a whole pot of soupchanges result
- ganjang (general) → tamari — Works in dipping contexts but lacks the assertive salt profile of guk-ganjangchanges result
Troubleshooting
Sauce lacks deep umami and tastes flat or beany
Insufficient fermentation time or weak mold development on the meju → Age longer (6+ months) and ensure the meju developed proper white or green Aspergillus during drying
Off, rancid, or putrid odors during fermentation
Brine salinity too low or contamination from a poorly sterilized vessel → Discard the batch; next time ensure at least 20% salt and thoroughly clean the onggi or use glass
White film or fuzzy growth on top of the brine
Wild yeast or surface mold; often benign early on but can turn spoilage if left thick → Skim carefully and keep the meju fully submerged under a weighted lid
Finished ganjang too salty for the intended use
Brine concentration too high or over-extraction time → Dilute with water or stock, or reduce the quantity in recipes that call for a lighter soy sauce