Lacto-Fermented Scallions

Pa-kimchi — 파김치 — is the version of kimchi that Korean home cooks make when they want results in 48 hours. Pa means scallion. The whole scallion goes in: roots trimmed, whites and greens together. You season it with gochugaru, fish sauce (or soy sauce for a vegan version), garlic, and sesame oil, then pack it and wait. Two to three days later, you have something genuinely different from any other ferment in your rotation.

The speed of pa-kimchi fermentation is structural. Scallions have very thin cell walls compared to cabbage or carrots. The salt penetrates quickly, the water activity drops, and LAB establish faster. The thin cell walls also mean the scallions go from raw to fermented without passing through a long intermediate stage — they go directly to tender-acidic, which is where you want them.

The umami factor is what separates this from other vegetable ferments. Fish sauce contains glutamates and nucleotides that drive savory intensity. When those compounds ferment alongside the scallion sugars and the gochugaru, the result is complex — acidic, spicy, funky, savory all at once. There's a reason pa-kimchi is a banchan staple. It makes everything around it taste better.

From a microbiology standpoint, kimchi fermentation is one of the most-studied LAB fermentations in the literature. A 2023 review in Critical Reviews in Food Science and Nutrition (PMID: 36718547) confirmed that kimchi LAB — principally Leuconostoc mesenteroides in early fermentation and Lactiplantibacillus plantarum as pH drops — reach 9–10 log CFU/g and demonstrate antioxidant, anti-inflammatory, and probiotic properties in human studies. A 2021 study in the Journal of Food Science (PMID: 34146398) found that capsaicinoids from gochugaru specifically shift the microbial community, increasing Lactobacillus sakei counts while modulating Leuconostoc — giving you a distinctive LAB profile that's different from plain brine vegetable ferments. A 2019 study in the Journal of Microbiology and Biotechnology (PMID: 31474094) quantified this further, showing that capsaicinoid content at realistic cooking concentrations (98–428 mg/kg) measurably influenced acidity, organic acid production, and the Lactobacillus-to-Leuconostoc ratio throughout fermentation.

The gochugaru isn't just heat. It's a fermentation modifier.

Instructions

1. 

   1

   Trim and salt the scallions

   Trim the root ends of the scallions and peel away any slimy or damaged outer layer. Leave the scallions whole — do not chop. Weigh them, calculate 2.5% salt, and sprinkle it over the scallions in a large bowl. Toss to coat and let sit for 10 minutes. The salt will slightly wilt the scallion greens and draw out surface moisture.

   Chemist's note

   Use gochugaru specifically — not cayenne, crushed red pepper, or smoked paprika. Gochugaru is a sun-dried Korean chili with a specific heat level, sweetness, and color profile. Substitutes will give you a different ferment with different LAB dynamics. It's worth getting the real thing.

2. 

   2

   Make the seasoning paste and coat the scallions

   In a small bowl, combine gochugaru, fish sauce, minced garlic, and optional sugar. Mix into a rough paste. Put on gloves — gochugaru stains everything. Grab a handful of scallions and drag them through the paste, coating the whites and greens. The whites absorb flavor faster; make sure they're well coated. The greens are more delicate and will carry mostly surface flavor.

   Chemist's note

   Fish sauce is not optional for authentic pa-kimchi — it's a fermentation accelerant and flavor amplifier. If you must go vegan, use a combination of soy sauce (for salt/umami) and a small piece of dried kelp (kombu) for glutamate depth. The microbial profile will be slightly different but still good.

3. 

   3

   Pack into a jar

   Bundle 4–5 scallions together and coil them into the jar. Repeat until the jar is packed. Press down firmly — you want the scallions compressed so they stay below any liquid. Add any remaining paste from the bowl. If there isn't enough liquid to cover, add 1–2 tablespoons of water. The scallions will express more liquid as fermentation progresses.

   Chemist's note

   Unlike brine ferments, pa-kimchi is a dry-seasoned kimchi — it doesn't have a lot of free liquid initially. That's correct. The scallions will weep more moisture during fermentation. Press them down daily with a clean spoon. By day 2 there should be more liquid than you started with.

4. 

   4

   Ferment 2–3 days at room temperature

   Ferment at room temperature, 68–72°F. Cover loosely or with an airlock lid. Press the scallions down once or twice per day. At 48 hours, taste a scallion — it should be pungent, tangy, spicy, and the greens should be limp and silky. The whites should still have some bite. At 72 hours you'll have a more pronounced acid flavor and softer whites. Either endpoint is valid depending on your preference.

   Chemist's note

   Pa-kimchi ferments very fast — faster than most kimchi because scallions have thin cell walls and less structural resistance to acidification. In warm weather (75°F+), 48 hours may be enough. In cooler conditions (below 65°F), you may want a full 3–4 days.

5. 

   5

   Refrigerate and serve

   Once pa-kimchi reaches your target acidity, move it to the refrigerator. Add sesame oil now if you want it — it doesn't ferment well but blooms beautifully in the cold. Serve as banchan alongside rice, add to ramen, chop into fried rice, or eat alongside grilled meats. The flavor deepens in the fridge over the first week. Eat within 2–3 weeks while the greens still have texture.

   Chemist's note

   Leftover pa-kimchi brine is gold. Use it as a base for salad dressings, marinades, or add a splash to a Bloody Mary. The liquid accumulates the organosulfur compounds from the scallions, the glutamates from the fish sauce, and the lactic acid from fermentation — a concentrated flavor base.