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

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Feeling beaten down by summer? Nutritious "doyo shijimi" now in the prespawning stage have been known since olden times as an ingredient that prevents summer weariness.

The small freshwater clams, known in Japan as "shijimi," are in season in summer and winter. 

This week, we'll show you how to prepare them in a red miso soup.

Since clams in soup produce good broth, there's no need to prepare a separate stock. The clams are cooked slowly in water to transfer their savory "umami" flavor into the soup.

To ensure your clams turn out tasty, wash them thoroughly before cooking. As shijimi inhabit fresh or brackish water, any sand remaining on the shell should be removed in saltwater with lower salinity than seawater and rinsed to remove odor.

Since your clams may squirt out water when you're scrubbing off the sand, it's a good idea to cover the container you rinse them in with newspaper. Akiko Watanabe, who supervised the cooking aspect of this week's recipe, says she washes hers in the bathroom.

Shijimi can be frozen and stored after the sand is removed. When using frozen clams, just plunk them directly into boiling water.

"Hatcho" miso uses soybean "koji" fungus matured for a long period. It's rich in flavor and has a faint astringency and sourness and tastes refreshing in the summer. A dash of sake will hide the smell of the sea and bring out the rich taste of shijimi.

BASIC COOKING METHOD

(Supervised by Akiko Watanabe in the cooking aspect and Midori Kasai in the cookery science aspect)

* Ingredients and cooking utensils (Serves 2)

150 grams shijimi, 1 tsp sake, 1 and 1/3 Tbsp Hatcho miso, 2 "mitsuba" stalks, flat container or deep bowl, sieve, pot, ladle, knife and cutting board, miso strainer

About 41 kcal and 1.4 grams salt per portion

1. Remove sand from clams. Pour weak saltwater (with salinity of about 1 percent that is 1/3 tsp salt per 200 ml water) in flat container or deep bowl and leave for more than 30 minutes (PHOTO A).

2. Wash clams by rubbing shells together, remove dirt on surface and place in sieve. Add clams, 400 ml water and sake in pot and place on medium heat. When it comes to a boil, turn to low heat. Occasionally remove the froth on top with ladle and keep heat low so few bubbles rise. Cook for 5 minutes (PHOTO B).

3. Cut mitsuba into 5-mm lengths. Prepare additional relishes of your choice such as finely chopped thin green onion ("hosonegi") and young leaves and shoots of Japanese pepper ("kinome") (PHOTO C). Powdered Japanese pepper ("sansho") and seven-flavor chili pepper also go well with the dish.

4. Turn off heat, place miso in strainer and strain by pressing with ladle. Turn heat on and bring to a quick boil. Serve in bowl and sprinkle with mitsuba.

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Akiko Watanabe is a cooking expert specializing in Japanese cuisine.
Midori Kasai is a professor at Ochanomizu University and chair of the Japan Society of Cookery Science.

ARRANGED VERSION

"Ushio-jiru" with small freshwater clams
Ushio-jiru is a type of soup made of seafood broth flavored with salt.

Remove sand from 150 grams shijimi, wash by rubbing shells together. Add shijimi, 400 ml water and 1 tsp sake in pot and place on medium heat. When it comes to a boil, lower heat, remove suds and quietly simmer for 5 minutes. Add a bit (about 1/3 tsp) of salt, bring to a quick boil and serve in bowl. Sprinkle with finely chopped thin green onion.

COOKERY SCIENCE

Clams such as shijimi, "asari" and "hamaguri" are rich in savory umami flavor components such as sweet amino acids and succinic acid and will turn into distinctive soups.

By adding fresh clams in cold water when cooking instead of hot, a good amount of umami components dissolve in the soup before it comes to a boil. Since clams are somewhat salty, add only a modest amount of salt.

Q&A

A 76-year-old Tokyo reader wrote in with a question about the horse mackerel in spicy sweet vinegar marinade introduced last week.

Question: The recipe says to "cook over low heat for 1 to 2 minutes and once it starts to brown …" but when I tried cooking on the element of my electric stove, the fish didn't cook in 2 minutes. Why?

Answer: In induction heating, magnetic lines cause the pot itself to heat up. Though it is high in thermal efficiency and has heating power that is comparable to gas stoves, how heat is transferred varies according to the material and size of the frying pan being used.

We hope our readers will take the heat level and cooking time in the recipe as a rough indication and, in the case of last week's horse mackerel dish, focus on the finish that should be "golden" as the main guide when cooking.