When I think of the quintessential Japanese dish, what comes to mind is a simple bowl of soup — not miso soup, although that, too, is very Japanese. Instead, my mind wanders to the clear soup known as suimono or, more commonly, osuimono with the honorific “o” prefix (osumashi is yet another name for it), that is a microcosm of all that washoku (traditional Japanese cuisine) stands for.
The soup is based on a well-balanced, umami-packed dashi, the foundation of most savory washoku dishes. In addition, the wandane (items placed in the soup) should ideally reflect the season in which the soup is being served and provide a good balance of flavor and texture: all the tenets of washoku in a bowl.
Let’s start with the dashi (soup stock) base. I have included dashi in many recipes in my articles over the years since it’s so fundamental to Japanese cuisine, but the dashi in osuimono should be made using the best konbu seaweed and katsuobushi (skipjack tuna flakes) you can get your hands on.
Konbu is a great source of glutamic acid and katsuobushi is an equally good source of inosinic acid: The two together provide a perfect balance of umami in a clear, slightly tinted broth that becomes the ideal base for osuimono.
The best types of konbu seaweed are makonbu (literally “real konbu”), which has a clean, refined flavor and is the variety most used by high-end washoku restaurants, and rishiri konbu, which is just slightly lighter in umami than makonbu.
And the best katsuobushi is honkarebushi. Katsuobushi is made via long process where katsuo (known as bonito or skipjack tuna in English) is dried, boiled, smoked and dried again. “Young” katsuobushi that has been dried for a brief period is sold as lower-grade arabushi, but when the arabushi is coated with a harmless mold and dried even further it becomes rock-hard, and the inosinic acid/umami becomes very concentrated.
This recipe is for a springtime osuimono that features wandane that reflect the season: pink shrimp and bamboo shoots, snow peas as the aomi (green accent) and green leaf mitsuba (Japanese parsley) as the tsuma or suikuchi (fragrant garnish). You may want to add an additional suikuchi, such as a sprinkle of citrusy sanshō Japanese pepper or a sprig of fresh sanshō leaf (kinome), for extra zing.
Always serve osuimono in a dark bowl, to highlight the colors of the wandane. Vegans may choose to use good quality dried shiitake mushrooms, which are a source of another umami component called guanylic acid, instead of the katsuobushi in the dashi, and use tofu or fresh shiitake mushrooms instead of the shrimp.
Springtime osuimono (clear soup)
Ingredients (2 large or 3 small portions)
For the dashi (soup stock):
• 500 milliliters cold water
• 10 grams konbu seaweed (a 15-centimeter square piece), makonbu or rishiri konbu preferred
• 10 grams honkarebushi katsuobushi (high-quality skipjack tuna flakes), equivalent to a large handful
For the wandane (soup ingredients):
• 1 teaspoon light (usukuchi) soy sauce
• ½ teaspoon salt
• 2 to 3 large fresh shrimp in their shells, such as black tiger
• 1 tablespoon potato starch or cornstarch
• 6 to 9 snow peas
• 4 to 6 slices boiled bamboo shoot (available in vacuum packs)
• 4 to 6 sprigs leaf mitsuba (Japanese parsley), with long stems attached
Make the dashi. Carefully wipe off any dirt or sand from the konbu seaweed with a tightly wrung-out kitchen towel. Put it in the cold water, and leave to soak in the refrigerator overnight. Put the water and konbu in a pan over medium heat.
When small bubbles start to form around the perimeter of the water, remove the konbu and bring the water to a boil. Turn off the heat and add the katsuobushi. Leave until the katsuobushi sinks to the bottom of the pan.
Line a strainer with paper towels or a coffee filter. Pour the liquid into the lined strainer, filtering out the katsuobushi. Rinse out the pan and return the strained liquid to it: This is the dashi. Add the soy sauce and salt.
Shell the shrimp, leaving the tails on. Make an incision in the backside of each shrimp and remove the intestines. Sprinkle the shrimp with the potato or cornstarch and rub to clean, then rinse off and pat dry.
Remove the strings, tops and tails from the snow peas. Cut the mitsuba stems to the same length as the peas and tie two mitsuba stems together into a loose knot, repeating with all mitsuba stems.
Heat the dashi over medium heat. When it comes to a boil, add the shrimp and simmer until just cooked through. Remove the shrimp and add the snow peas. Cook for a minute and remove.
Heat the soup up again if needed. Place a shrimp, two slices of bamboo shoot, three snow peas and a knotted mitsuba into two large or three regular-sized lacquered (or lacquer-type) Japanese-style soup bowls. Ladle the soup carefully into each bowl, and cover with a lid if one is available. Serve immediately.