Japanese Clear Soup with Tofu, Mushrooms, and Mitsuba (Osuimono)

This soup highlights the flavor of kombu and katsuobushi dashi and is delicately seasoned with soy sauce and other seasonings. The smooth texture of the tofu is complemented by the aroma of mushrooms and the refreshing flavor of mitsuba, creating a delicate taste.

• by Yuko Ihara

“Osuimono” (お吸い物) is a classic Japanese soup that lets you enjoy the fine flavor of katsuobushi and kombu dashi. For this reason, it is not heavily seasoned, but finished elegantly with a small amount of soy sauce or other seasoning. Main ingredients such as tofu or seafood are paired with mushrooms or vegetables, and an aromatic garnish called “suikuchi” (吸い口) is added at the end, allowing you to enjoy seasonal combinations.

Dashi and soy sauce are inseparable. The inosinic acid found in katsuobushi used for dashi and the glutamic acid found in soy sauce work together to create a synergistic umami effect, resulting in deeper umami. The aroma of soy sauce is also an important element that shapes the flavor of osuimono.

When simmering kombu, use low heat to slowly draw out its umami, and avoid bringing it to a boil. This helps create a clear-tasting dashi without any unwanted flavors. Also, dashi is at its most flavorful when freshly made, so it is recommended to make it right when preparing the dish rather than making it in advance.

Katsuobushi and Kombu Dashi:

Kombu - 5g (0.2 oz.)
Katsuobushi / dried bonito flakes - 10g (0.4 oz.)
Water - 500ml (16.9 fl oz.)
*Use 300ml of the prepared katsuobushi and kombu dashi

Kikkoman Soy Sauce - 1 tsp
Salt - 1/4 tsp

Maitake mushrooms - 30g (1 oz.)
Mitsuba - 4 sprigs
silken (soft) tofu - 50g (1.8 oz.)

“Suikuchi” (吸い口) refers to aromatic vegetables or citrus added as a finishing garnish to Japanese-style clear soup (”osuimono”). It helps bring out the flavor of the soup and adds a subtle fragrance. In Japanese cuisine, seasonality is highly valued, so seasonal ingredients are used as suikuchi: sansho buds / kikome in spring (far left in the photo), myoga in summer (second from the left), green shiso (third from the left), and yellow yuzu in winter (right). Each ingredient is cut into a pleasant, easy-to-eat size; for citrus, thinly shaved peel is used.

Osuimono is usually made by preparing dashi first, but you can also make an “osuimono-style” soup with the flavor of dashi simply by pouring hot water over katsuobushi / dried bonito flakes. Just place katsuobushi, sprouts, tomatoes, or other ingredients in a bowl, pour in hot water, and season with soy sauce or other seasonings. The katsuobushi can be eaten on its own as well.

At Japanese restaurants, clear soup / osuimono is often served in a lidded bowl. This is not only to keep the soup warm, but also to let guests enjoy the aroma of dashi that gently rises the moment the lid is opened. When enjoying it at a restaurant, be sure to pay attention to the fragrance as well.

Having lived in England and the U.S., Yuko Ihara is well-versed in a wide range of culinary genres. As a culinary researcher, she creates dishes for magazines and books, develops corporate menus, and also engages in product development and food consulting. She introduces easy-to-follow tips on how to make delicious food at home, emphasizing the importance of seasonality and healthful eating. When travelling, she loves to search for delicious vegetables and ingredients.

Instagram: @iharayukoo