Editor’s note: The theme of Gohan Lab is to help people make simple, tasty “gohan” (meals).

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Our goal this time is to make dashi stock using “katsuobushi” (boiled, dried, smoked and fermented skipjack tuna) and dried “kombu” kelp in a simple manner and use it casually in our familiar dishes. We could call it the “daily dish stock.”

It may be different from the rich first stock used by the professionals, but the freshly made stock is so aromatic that it will be a delicacy in itself.

First, daikon radish and thin deep-fried tofu will be simmered to offer a juicy tastiness.

To make dashi, choose shaved katsuobushi and dried kombu that are reasonably priced so you can use them without hesitation. We bought them at a large supermarket, and the cost for this particular installment was 70 yen (64 cents). When making clear soup with the first stock, the rule is “not to boil to extract” and “not to turn it cloudy,” but in the case of “daily dish stock” the umami will be squeezed out to the last drop.

Now it’s time to cook the daikon radish. Slice in a thickness that you can bite into and parboil in the microwave before cooking for 15 minutes in the pot. The soy sauce flavor will coat the surface, but it will remain fresh and juicy inside. The thin, deep-fried tofu will absorb the stock and puff up, giving you the satisfaction of having eaten the dashi.

Boiled komatsuna leaves were immersed in the remaining stock. The vegetable with a light flavor will embrace the umami and remind you of the goodness of Japanese-style food.

‘Karebushi’ offers complex umami and aroma

Masayuki Ukai, who runs Ukai Shoten, a wholesaler in Tokyo’s Hongo district catering to restaurants, offered some pointers on the choice of shaved katsuo.

The material used to make katsuo shavings can be roughly divided into two kinds. One is “arabushi,” where the fish is filleted, simmered, smoked and dried. It is said to make up 90 percent of the total trading volume of katsuobushi. Products made by shaving arabushi are labeled “katsuo-kezuri-bushi” or “hanakatsuo.”

The other kind is “karebushi,” where mold is applied to the arabushi that is left to ferment and mature. The products are labeled differently as “katsuo-karebushi-kezuri.”

Karebushi shipped after mold is applied more than three times are normally more complex than arabushi in umami and aroma. Ukai says he allows the stocked karebushi to sit at the store and shaves when the time is right. The freshness of the shavings is crucial. He advises buying in small amounts and storing in the freezer.

BASIC COOKING METHOD

(Supervised by Akiko Watanabe in the cooking aspect and Hiroya Kawasaki in the cookery science aspect)

* Ingredients and cooking utensils (Serves two)

For katsuo-kombu dashi: 6 grams shaved katsuo (katsuo-kezuri-bushi), 5 cm square (2 grams) dried kombu kelp, 2 and 1/2 cups water

For daikon radish simmered in dashi stock: 1 and 1/2 cups katsuo-kombu dashi, 200 grams daikon radish, 1 thin deep-fried tofu (abura-age), 1 Tbsp light soy sauce (dark soy sauce works as well), 2 tsp sweet mirin sake, Japanese pepper powder (kona-sansho) or seven-color chili pepper (shichimi)

1. Have shaved katsuo and kombu ready (PHOTO A). Add water and kombu kelp to pot (leave for a while if time permits) and place over low heat. Remove kelp right before boiling. Bring to a boil and add shaved katsuo, mixing briefly with chopsticks so shavings sink. Simmer over low heat for about 2 minutes.

2. Run through sieve, squeeze shavings by pressing down with chopsticks (PHOTO B). Use 1 and 1/2 cups for the daikon dish and the rest to season boiled vegetables.

3. Peel daikon radish, cut in half lengthwise, then into 1-cm-thick half-moons. Place on dish, pour 1 Tbsp water, cover with plastic wrap and microwave (600W) for 5 minutes until soft enough to allow bamboo skewer through smoothly. Drain in sieve. Pour hot water on deep-fried tofu to remove oil, squeeze out water and cut into 3-cm squares.

4. Add stock and daikon to pot and place over medium heat and bring to a boil. Place drop lid and cook over low heat for 10 minutes. Add deep-fried tofu, light soy sauce and sweet mirin sake. Place drop lid and simmer for 5 to 6 minutes (PHOTO C). Turn off heat when soup shows luster and has the right strength in taste. If preferred, sprinkle Japanese pepper powder or shichimi.

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Akiko Watanabe is a cooking expert specializing in Japanese cuisine.

Hiroya Kawasaki studies the science of tastiness and cooking methods at Ajinomoto Co.’s Institute of Food Sciences and Technologies.

ARRANGED VERSION

The type of dish known as “ohitashi” may incorporate seasonal green leafy vegetables as well as “ingen” (common bean), bell pepper and more. Mix 1/2 cup of katsuo-kombu dashi with 1 Tbsp soy sauce and 1 tsp sweet mirin sake. Cut off root end of 100 grams of komatsuna and rinse. Bring generous amount of water to a boil in a pot, add komatsuna and when it boils again, cook for 2 to 3 minutes, remove and immerse in water. Tightly squeeze out water. Cut into lengths of 4 cm and immerse in dashi. It can be stored in the fridge for two to three days.

COOKERY SCIENCE

The umami is more intense when we taste its two components, the glutamic acid of kelp and inosinic acid of dried katsuo, at the same time. This is the “synergistic effect of umami.” An experiment showed that the effect was the highest when the ratio of the two components was one to one. When the dashi stock served at a Japanese restaurant in Kyoto was analyzed, the ratio is said to have been one to one.

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From The Asahi Shimbun’s Gohan Lab column