Spicy Konnyaku: Japanese Yam Cake

Spicy Konnyaku: Japanese Yam Cake

The Spruce / Christine Ma

Prep: 10 mins
Cook: 10 mins
Total: 20 mins
Servings: 4 servings
Nutrition Facts (per serving)
184 Calories
3g Fat
37g Carbs
3g Protein
Show Full Nutrition Label Hide Full Nutrition Label
Nutrition Facts
Servings: 4
Amount per serving
Calories 184
% Daily Value*
Total Fat 3g 4%
Saturated Fat 1g 3%
Cholesterol 13mg 4%
Sodium 418mg 18%
Total Carbohydrate 37g 13%
Dietary Fiber 4g 14%
Total Sugars 8g
Protein 3g
Vitamin C 12mg 61%
Calcium 27mg 2%
Iron 1mg 4%
Potassium 703mg 15%
*The % Daily Value (DV) tells you how much a nutrient in a food serving contributes to a daily diet. 2,000 calories a day is used for general nutrition advice.
(Nutrition information is calculated using an ingredient database and should be considered an estimate.)

Konnyaku is the Japanese term for the vegetable or plant also known as devil’s tongue, konjac, konjak, konjaku, konnyaku potato, voodoo lily, or elephant yam. Konnyaku also refers to the prepared food where the root of the konjac plant is made into a rectangular block of jelly-like yam cake or noodles.

In Japanese cuisine, konnyaku is as common as short-grain rice and is used in many different types of Japanese dishes. However, it is quite interesting that it was hyped as a diet and weight-loss food at one point in the early 21st century resulting in a “konnyaku boom.” This was in large part because konnyaku has zero fat with practically no calories, yet it is filling because of its high fiber content.

As far as taste and texture are concerned, it is not uncommon for folks to either love it or hate it. Konnyaku is bland, and almost without any flavor, yet it has a distinct texture that is similar to a solid jelly-like state and is quite springy and chewy. To some, the texture alone makes konnyaku completely unpalatable. However, often this same texture is what appeals to the Japanese and others who fancy this unique food.

This food is a staple of Japanese cuisine and is believed to have existed since the sixth century.


  • 1 (14-ounce) package Japanese konnyaku, yam cake

  • 2 tablespoons water, or katsuo bonito dashi

  • 3 teaspoons dashi-seasoned soy sauce

  • 1 to 2 teaspoons soy sauce, to taste

  • 1/8 teaspoon Japanese 7-chile pepper, shichimi togarashi

Steps to Make It

  1. Gather the ingredients.

    Spicy Konnyaku: Japanese Yam Cake ingredients

    The Spruce / Christine Ma

  2. Slice konnyaku into thick matchsticks or other desired size.

    Slice konnyaku into thick matchsticks on a cutting board

    The Spruce / Christine Ma

  3. Heat a nonstick pan over medium heat. Add water, soy sauce, dashi seasoned soy sauce, and konnyaku. Stir continuously.

    water, soy sauce, dashi seasoned soy sauce, and konnyaku with konnyaku in a pan

    The Spruce / Christine Ma

  4. Add 7-chile pepper (shichimi togarashi), and braise until most of the liquid evaporates, about 6 to 8 minutes. Add more soy sauce to taste.

    konnyaku braising in the sauce with shichimi togarashi

    The Spruce / Christine Ma

  5. Remove from heat and serve spicy konnyaku on individual small plates. Garnish with additional 7-chile pepper (shichimi togarashi).

    Spicy Konnyaku: Japanese Yam Cake on plates

    The Spruce / Christine Ma


  • Because of the bland nature of konnyaku, it easily adapts to the seasonings and ingredients of the dish in which it is included. It is quite versatile in soups, in simmered or braised dishes, and in rice dishes such as chirashi sushi (scattered or mixed rice) or takikomi gohan (seasoned steamed rice). Konnyaku is also capable of “holding its own” as a stand alone okazu, or side dish, as is the case in this spicy konnyaku recipe. 
  • Konnyaku is available for sale in the refrigerated section of Japanese markets, as well as in other Asian grocery stores. Konnyaku can be found in flat, rectangular 10-ounce blocks and will be labeled either black (which is a light gray-brown color) or white. It is known as “ita konnyaku.” Konnyaku is also available as noodles, again in black or white, and is known as “shirataki.”
  • The spicy konnyaku dish featured in this article is a wonderful addition to any Japanese meal as a side dish or appetizer. It is also a great item to include in a bento (Japanese lunch box).

Recipe Variations

  • For this spicy konnyaku recipe, blocks of ita konnyaku were sliced into thick, short noodles, but if you prefer, this may be substituted with shirataki noodles. If you do try it with the shitaki noodles, make sure that you cut the noodles into shorter, bite-sized pieces as the noodles are extremely long and difficult to eat if left as is.
  • Substitute water with dashi stock, especially in the event seasoned soy sauce (dashi shoyu), is not used. Or use 1/8 teaspoon bonito dashi powder combined with water.
  • Make it vegetarian or vegan by substituting katsuo (bonito fish) dashi with konbu (kelp) dashi.