Spicy Konnyaku: Japanese Yam Cake

Spicy Konnyaku (yam cake)

Judy Ung

Prep: 10 mins
Cook: 10 mins
Total: 20 mins
Servings: 4 servings

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 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 which is similar to a solid jelly-like state which 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-chili pepper (shichimi togarashi)

Steps to Make It

  1. Gather the ingredients.

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

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

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

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


  • 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 grey-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.