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Pumpkin And Tofu Miso Soup: Solve Debate Over Dashi First

Bowls of dashi. Credit: Sonoko Sakai

Bowls of dashi. Credit: Sonoko Sakai

Every week, I make a pot or two of fresh stock, but it doesn’t involve cooking bones, meat or chicken in water over low heat for hours. Mine takes less than 20 minutes to put together, yet it is the foundation of all my cooking. It’s dashi, the quintessentially Japanese stock, made of dried bonito and konbu seaweed.

It forms the base of my breakfast miso soup, or part of a sauce to make stews and curries, and even a seasoning for my salad dressings. Dashi is a natural umami enhancer that never overwhelms, and not a drop of oil is used in its making, which makes for a clean taste. When Michelin three-star French chefs Alain Ducasse and Joël Robuchon opened their restaurants in Japan and learned the Japanese didn’t care for cream, butter and oily sauces, they incorporated dashi. Now, Kanbutsu-ya — dashi specialty shops in Japan — are seeing a surge in overseas sales of katsuobushi, dried bonito and konbu seaweed.

Theories about making dashi

People have different schools of thought about how to make a good dashi. The most popular combination is bonito flakes and konbu seaweed. Every Japanese chef or cook will agree the konbu seaweed goes into the pot of water first and is then plucked out of the water before it reaches its boiling point. Then the bonito flakes are added.

Some chefs will argue that when making primary dashi, the mixture should cook over low heat for just a few minutes. Others will tell you to completely turn off the heat once the flakes are added and let them steep in the liquid like tea. Ignoring these steps and instead overcooking the dashi ingredients or pressing down the konbu and bonito flakes with a spatula could turn your dashi cloudy and fishy.

Secondary dashi, a weaker broth but just as useful as primary dashi, can be made with used konbu and bonito flakes from the primary dashi. I throw these used strips of konbu into my salads and pickles, or munch on them straight. It’s a great source of fiber. My kitty loves bonito flakes dried or cooked, so there is never any waste.

The changing form of katsuobushi – dried bonito

In the old days, every Japanese household used dried bonito whole and shaved its own bonito flakes with a katsuobushi kezuriki — a plane tool. When my father was drafted as a soldier during World War II, one of the things my grandmother gave him to take on his arduous journey was a block of dried bonito, or katsuobushi. She figured if he got hungry, he could lick the block or break it with a hammer and cook the pieces in water to make a nourishing soup. Not exactly like beef jerky, but it was a great survival food.

Karebushi, or dried bonito. Credit: Sonoko Sakai

Karebushi, or dried bonito. Credit: Sonoko Sakai

The process of making katsuobushi is laborious. Fish is cleaned, sliced into fillets, cooked and smoked, and some go through another step where the smoked fillets are shaved, inoculated with a beneficial mold and sun-dried to produce a katsuobushi of extraordinarily rich umami flavors.

Dashi made with such dried bonito — called karebushi or hongarebushi – is tantalizingly fragrant, but it can take as long as six months to produce a single karebushi, and such artisans are sadly disappearing from Makurazaki, Kagoshima, on the island of Kyushu, Japan, where most of the production takes place.

These days, Japanese chefs and cooks rely on pre-shaven bonito flakes sold in packages. While the pre-shaven flakes don’t compare in flavor to the freshly shaven flakes, they are pretty good, and that is what you can find in the U.S.

I store bonito flakes in the refrigerator and try to use them up quickly. What you want to avoid is using powdered dashi that contains flavor enhancers and preservatives. You can also purchase dashi packs, which resemble tea bags. Some are made of all-natural ingredients. I recommend buying pre-shaven katsuobushi and konbu seaweed and making dashi from scratch, as it really doesn’t take long to assemble it.

The synergy between konbu and bonito flakes

You can make dashi with a single ingredient, but a combination of ingredients such as konbu and bonito flakes does wonders for the flavor. The naturally occurring glutamic acid in konbu and the inosinic acid in bonito flakes have a synergistic effect on the umami scale. In this case, one plus one doesn’t not equal two but three, five or seven. Add to that equation dried shiitake mushrooms, another ingredient rich in glutamic acid, and the stock will have an almost meaty flavor.

What to look for when you buy konbu and bonito flakes

Konbu seaweed has a white powdery surface. It’s the essence of konbu, so don’t wash it off. If the seaweed looks dusty, take a well-wrung cloth and give it a gentle wipe. Keep konbu in a plastic bag away from moisture.

Konbu seaweed. Credit: Patrick Gookin

Konbu seaweed. Credit: Patrick Gookin

With bonito flakes, you want to get a large bag (80 grams to 100 grams) that contains long, shiny shavings. You don’t want bonito flakes that look yellowish and flat — that means they are old and oxidized. Some bonito flakes contain more red meat than white meat, and those will taste slightly smokier and meatier. Some bonito flakes also include other fish, like saba (dried mackerel) shavings, which also make for good dashi.

Once opened, store the bonito flakes in the refrigerator and try to use them up as quickly as possible. And you will if you practice the dashi ritual like I do.

Basic Dashi

Makes 3½ cups, or four servings of stock to make miso soup. Dashi will keep fresh for three to five days in the refrigerator, so you can make it in advance and just add miso paste and vegetables for a quick breakfast of miso soup.


Chobei Yagi, the owner of Yagicho, a 276-year-old dashi shop in Tokyo, shows the store's display of dried bonito. Credit: Sonoko Sakai

Chobei Yagi, the owner of Yagicho, a 276-year-old dashi shop in Tokyo, shows the store’s display of dried bonito. Credit: Sonoko Sakai

3-inch piece of konbu seaweed

4 cups water

4 cups of loosely packed bonito flakes


1. Using scissors, make several crosswise cuts in the konbu. This helps to extract the flavor during cooking.

2. Place the konbu and water in a medium saucepan and bring to a boil.

3. Cook over medium heat until the water almost boils. Remove konbu just before the water boils to avoid a fishy odor.

4. When the water boils, turn off the heat then add bonito flakes. Do not sitr. Let stand for three to five minutes to let the flakes steep, then strain the dashi through a very-fine mesh sieve or a sieve lined with cheesecloth or a paper towel. Don’t press the bonito flakes because it will cloud the dashi. Your primary dashi is now ready for use.

Note: To make a secondary dashi, use the bonito flakes and konbu seaweed from the primary dashi. Cook them in 4 cups of water over medium-low heat for five to eight minutes. Follow the straining technique used for the primary dashi. You can use secondary dashi for making more miso soup or use it to make curries, stews and salad dressings.

Pumpkin and Tofu Miso Soup


3½ cups dashi (recipe above)

¼ kabocha pumpkin, peeled and sliced thinly into ¼-inch thick bite-size pieces

3 to 4 tablespoons koji or mugi, white or red miso

½ a block of tofu, soft or firm

1 scallion sliced thinly


1. Bring the dashi and kabocha to a boil in a medium saucepan, then reduce the heat to maintain a simmer until the kabocha is tender.

2. In a small bowl, dissolve the koji or miso in a few tablespoons of the warm dashi. Add the mixture to the saucepan. Taste and add more miso paste, dashi or water, depending on how strong the soup tastes.

3. Add the tofu and simmer for a minute. Turn off heat.

4. Pour the soup into individual bowls and garnish each bowl with scallions. Serve immediately.

Top photo: Bowls of dashi. Credit: Sonoko Sakai

Zester Daily contributor Sonoko Sakai is a Japanese food educator, writer and producer, as well as a mobile Japanese cooking teacher and soba maker, who divides her time between Los Angeles; Tehachapi, Calif.; and Tokyo. She has contributed stories and recipes to the Los Angeles Times, the Chicago Tribune and Saveur. She is passionate about making soba by hand and is the founder of Common Grains. She is currently writing "Rice Craft, Adventures in Onigiri, Japanese Artful Fingerfood" (Chronicle Books -- to be published in fall of 2016).