Bracken in Korean food is gosari (고사리), the young stems of bracken fern that are dried, rehydrated, and cooked into side dishes, soups, and rice bowls. If you’ve eaten bibimbap at a Korean restaurant, you’ve almost certainly had it: those dark brown, slightly chewy strands nestled among the other toppings. Gosari is one of the most traditional ingredients in Korean cooking, prized for its uniquely meaty texture and deep, earthy flavor.
What Gosari Actually Is
Gosari comes from the bracken fern, Pteridium aquilinum, one of the most common ferns in the world. What Koreans eat is the young, tightly curled stem of the plant, harvested in spring before the fronds unfurl. You might also see these called fernbrake or fiddleheads, though gosari specifically refers to bracken rather than other edible fern species.
Fresh bracken has a very short season, so Koreans have traditionally blanched and sun-dried the stems until they shrink into thin, dark brown threads. Drying does more than preserve them for year-round use. It concentrates and deepens the flavor in a way you won’t get from the fresh plant, similar to how drying mushrooms intensifies their taste. Once dried, gosari keeps in a pantry for months.
How It Tastes and Why Cooks Love It
Cooked gosari has a texture often described as meaty or slightly chewy, closer to a tender piece of beef tendon than to any leafy vegetable. The flavor is mild, earthy, and savory, which is why it pairs so well with bold Korean seasonings like soy sauce, sesame oil, and garlic. It absorbs whatever it’s cooked with, acting almost like a sponge for the surrounding sauce.
This combination of chew and flavor absorption makes gosari unusually satisfying as a plant-based ingredient. Nutritionally, fiddlehead ferns are surprisingly protein-rich for a vegetable: a cup of cooked ferns provides about 6 grams of protein along with 3 grams of fiber and over 500 milligrams of potassium, all for just 46 calories.
Where You’ll Find It in Korean Dishes
Gosari shows up in three main places in Korean cuisine:
- Gosari namul: The most common preparation. The rehydrated fern is sautéed with soy sauce, minced garlic, sesame oil, and sometimes a pinch of sugar. This side dish (banchan) appears on everyday tables and, importantly, on the ancestral memorial service table (charyesang), where it holds cultural and ceremonial significance.
- Bibimbap: Gosari namul is one of the classic toppings in traditional bibimbap, arranged alongside other seasoned vegetables over rice. It provides the earthy, chewy contrast to crisper vegetables like bean sprouts and zucchini.
- Yukgaejang: This fiery, red-hued beef soup uses long strands of gosari alongside shredded beef and scallions. The fern’s texture holds up well in the spicy broth.
How to Buy It
At a Korean grocery store, you’ll typically find gosari in three forms: dried, pre-soaked, or occasionally fresh. Dried is the most common and the most practical choice, since it stores easily and has the deepest flavor. Look for thin, dark brown strands that feel pliable rather than brittle and dustite. Pre-soaked gosari saves time but won’t keep as long, so use it within a few days of purchase.
To prepare dried gosari, you soak it in water for several hours (or overnight) until the stems soften and plump up, then boil it before seasoning. This soaking and boiling process isn’t just about texture; it’s also essential for safety.
Why Proper Preparation Matters
Raw bracken fern contains a naturally occurring compound called ptaquiloside, which is a known carcinogen in animal studies. This is why no Korean recipe calls for eating gosari raw. The traditional preparation method of soaking, boiling, and often drying beforehand isn’t accidental: it systematically breaks down this compound.
Research published in the journal Toxics measured exactly how effective this process is. Soaking dried bracken in water for four hours, then boiling for 20 minutes, reduced ptaquiloside levels by at least 94%. The longer the boil time and the more water changes during soaking, the lower the residual levels. Japanese cooks take this a step further by boiling bracken with wood ash or baking soda, which accelerates the breakdown.
A 1985 study on processed bracken found that while the carcinogenic activity was “reduced markedly” through traditional cooking methods, trace activity could still be detected in lab animals fed large quantities. In practical terms, the amounts consumed in a normal diet after proper preparation are vastly lower than anything used in those animal studies. The key takeaway is straightforward: always soak and boil gosari thoroughly before cooking with it. Never eat it raw or lightly rinsed.
Preparing Gosari Namul at Home
If you’ve bought dried gosari, start by soaking it in cold water for at least four hours, ideally overnight. The stems should swell to roughly double their dried size and feel soft when you bend them. Drain the soaking water, then boil the gosari in fresh water for 20 minutes or more. Drain again and let it cool enough to handle.
From here, cut the stems into roughly 3-inch lengths. Sauté them in a pan with a little sesame oil, then add soy sauce, minced garlic, and a splash of water or stock. Cook over medium heat for several minutes until the seasonings are fully absorbed. Finish with a final drizzle of sesame oil and a sprinkle of sesame seeds. The finished namul should be glossy, deeply savory, and pleasantly chewy, nothing like the dry brown threads you started with.
Leftover gosari namul keeps well in the refrigerator for several days and actually improves as the flavors meld, making it an ideal dish to prepare ahead of time.