Korean yams, also known as nagaimo or ma in Korean, are a popular root vegetable originally from Asia. They have a sticky, slimy texture when raw that becomes soft and chewy when cooked. Korean yams can be prepared in many ways and make a tasty, nutritious addition to a variety of Korean dishes.
What are Korean yams?
Korean yams (Dioscorea oppositae) are a type of root vegetable native to Asia. They are long, cylindrical tubers with brown, bumpy skin and creamy white flesh. When raw, the flesh is extremely sticky and slimy due to its high mucilage content. Once cooked, Korean yams develop a soft, starchy texture similar to a baked potato.
Compared to other yams, Korean yams tend to be longer and thinner. They also have a less sweet, more neutral flavor. Their texture lends well to grinding, shredding, boiling, and pan-frying after cooking. In Korean cuisine, ma is valued for its sticky texture and ability to add body to soups, stews, and porridges.
Where do Korean yams come from?
Korean yams are native to Asia, likely originating in China before spreading to Korea, Japan, and other nearby countries. China remains the world’s largest producer of nagaimo yams today, though they are also grown commercially in Japan and Korea.
In Korea, ma are grown in the southern regions of the peninsula from late fall to early spring. They are typically harvested by hand once the stems and leaves have died back. Most Korean grocery stores stock ma during its peak season of October through January.
Nutrition and Health Benefits
Korean yams are highly nutritious root vegetables. Some of the key nutrients found in a 100g serving of cooked ma include:
- 116 calories
- 0 grams fat
- 28 grams carbohydrate
- 3 grams protein
- 3 grams dietary fiber
- 18% DV vitamin C
- 15% DV manganese
- 12% DV vitamin B6
- 11% DV potassium
Compared to regular potatoes, Korean yams contain higher amounts of vitamin C, potassium, and manganese. They are a starchy vegetable but with very little fat.
Some research suggests Korean yams may provide certain health benefits, including:
- Improved digestion: Korean yams contain a type of soluble fiber called mucilage, which can help relieve constipation and promote regularity.
- Blood sugar control: The fiber in ma slows digestion, preventing blood sugar spikes after eating.
- Lowered blood pressure: The potassium in Korean yams may help lower high blood pressure.
- Immune supporting: Vitamin C promotes immune health and fights inflammation.
How to Select Fresh Korean Yams
When shopping for fresh Korean yams, look for tubers that are:
- Firm and heavy – Avoid yams with wrinkled, mushy spots.
- Smooth and brown – Smaller “hairy” roots tend to be more fibrous.
- Medium to large in size – Yams smaller than your pinky finger will be drier.
- Free from cuts, cracks, or bruises.
The skin color can range from light tan to dark brown. Avoid greenish yams as they may have a bitter taste.
How to Store Korean Yams
Fresh ma should be used within 2-3 weeks of purchase. To extend their shelf life:
- Store whole, unpeeled yams in a cool, dark place around 55°F.
- Do not refrigerate. The cold damages the texture.
- Leave them loose or wrap in paper – Avoid plastic bags which trap moisture.
- Once cut, wrap pieces in plastic and refrigerate for up to 5 days.
How to Prepare Korean Yams
Before cooking, Korean yams must be peeled and soaked in vinegar water to remove some of their stickiness. Here is the basic process:
- Trim off both ends of the yam.
- Stand the yam on one end and peel off the skin using a paring knife or vegetable peeler.
- Cut the yam into the desired shape: slices, matchsticks, cubes, etc.
- Soak the pieces in cold water mixed with a splash of vinegar for 5-10 minutes.
- Drain, rinse, and pat dry – the pieces will be less slippery.
- The yams are now ready to cook as desired.
Tips for Preparing Ma
- Use a stainless steel knife and cuttings board – the yam sticks to other surfaces.
- Work over a bowl to catch the sticky residue washing off the yam.
- Soak for longer to remove more stickiness if desired.
- Add a teaspoon of salt to the vinegar soak for extra slime removal.
- Wear gloves if you don’t want yam residue on your hands.
Cooking Methods
Korean yams become soft and chewy when cooked. They work well in soups, stir-fries, and steamed or sautéed dishes. Here are some of the most common cooking methods:
Boiling
Boiling tenderizes ma nicely to be used in soups or stews. Add peeled, cut yams to your broth or sauce and simmer until soft, 15-20 minutes.
Steaming
Steaming keeps Korean yams soft and sticky for use in purees or porridges. Place cut yams in a steamer basket over boiling water and steam for 15 minutes, until fork tender.
Sautéing
Pan-frying adds flavor and caramelization. Coat peeled, cut yams in a little oil, broth, or sauce and sauté over medium-high heat for 6-8 minutes.
Roasting
Roasting brings out the natural sweetness of ma. Toss peeled, cut yams with oil and seasonings and roast at 400°F for 20-25 minutes until lightly browned.
Baking
Baking whole yams makes them soft and sweet. Prick whole yams with a fork, bake at 400°F for 60-70 minutes, then scoop out the flesh.
Grinding
Cooked, peeled ma can be easily ground or mashed into a sticky paste to add texture to dishes.
Common Ingredients and Flavors
Korean yams pair well with complementary ingredients like:
- Meats: Beef, pork, chicken
- Seafood: Clams, squid, fish cakes
- Vegetables: Mushrooms, spinach, carrots, onions
- Seasonings: Sesame oil, garlic, ginger, soy sauce, gochujang
- Grains: Short grain rice, sweet rice, barley
Their mild flavor takes on surrounding tastes easily. Sweet or spicy seasonings add lots of flavor.
Popular Korean Yam Dishes
Here are some favorite Korean recipes featuring ma as a main ingredient:
Japchae
Sweet potato glass noodles stir-fried with meat, veggies, and seasoned ma.
Jeyuk Bokkeum
Spicy stir-fried pork with grated yams and vegetables.
Gamja Onigiri
Fried Korean yam rice balls coated in sesame seeds.
Ma Jun
Battered, fried yam patties often served with dipping sauce.
Hobakjuk
Thick, creamy Korean porridge made with ma and rice.
| Dish | Main Ingredients | Cooking Method |
|---|---|---|
| Japchae | Sweet potato noodles, beef, spinach, carrot, onion, ma | Stir-frying |
| Jeyuk Bokkeum | Pork, ma, onion, shiitake mushrooms, carrots, garlic | Stir-frying |
| Gamja Onigiri | Short grain rice, ma, sesame oil, sesame seeds | Frying |
| Ma Jun | Ma, flour, egg, breadcrumbs, vegetable oil | Frying |
| Hobakjuk | Ma, glutinous rice, salt, water | Boiling |
Tips for Cookng with Korean Yams
- Soak raw yam pieces before cooking to reduce sliminess.
- Undercook slightly for the best texture in stir-fries or soup.
- Add grated yam at the end of cooking if you want it to stay intact.
- Roast or pan-fry for a few minutes to drive off excess moisture.
- Blend or mash cooked yams for a thickener or binder.
- Season with sesame oil, soy sauce, garlic, ginger, salt and pepper.
Where to Buy Korean Yams
Fresh ma can be found seasonally in the produce sections of most Asian grocery stores. Outside of Asia, look in:
- Chinese, Korean, or Japanese grocery stores
- Asian supermarkets like H Mart or Lotte Mart
- Farmers markets in areas with Asian populations
The yams are sometimes labeled as nagaimo, yamaimo, Chinese yam, or Japanese mountain yam. Buy them fresh whenever possible as the texture is best.
Dried, frozen, and pre-shredded ma can also be found at many Asian groceries but may have a drier, less sticky texture once reconstituted.
Substitutions for Korean Yams
If you can’t find fresh Korean yams, try substituting:
- Yukon gold or russet potatoes – Less sticky but similar flavor.
- Taro root – Denser but becomes soft when cooked.
- Whole wheat flour – Adds body and a mild flavor.
- Sweet potato starch – Provides thickness and binding.
- Arrowroot powder – Used to thicken liquids.
While not exactly the same, these swaps can mimic some of the properties of Korean yams in a pinch! Adjust the ratios when substituting.
Conclusion
With their unique sticky yet soft texture and neutral flavor, Korean yams make a tasty addition to many Korean dishes. Prepare them by peeling, soaking, and cooking through methods like boiling, sautéing, or steaming. They can be enjoyed in soups, porridges, stir-fries, and side dishes. Look for fresh ma at Asian grocery stores and try some of the traditional recipes using this healthy, delicious root vegetable.
