Suimono: the clear soup that tests a kitchen

The first thing a good suimono gives you isn't a taste. It's a smell. You lift the lid of a small lacquer bowl, a little cloud of steam escapes, and with it comes the scent of the sea and a bright flicker of citrus. Only then do you look down and see the soup: almost perfectly clear, with one carefully placed morsel resting in the middle.

Suimono (吸い物), or osuimono with the polite prefix, is Japan's clear soup. The name comes from suu (吸う), to sip. It's the quiet sibling of miso soup, and in many ways the more demanding one.

A broth with nowhere to hide

Miso soup can forgive a slightly rough dashi; the miso covers a lot. Suimono can't. Its foundation is usually ichiban dashi (一番出汁), the "first dashi": the most delicate extraction of kombu and katsuobushi, pale gold and fragrant, made quickly so that only the cleanest flavours come through. Our dashi guide walks through how it's made.

The seasoning is deliberately restrained: salt, a few drops of soy sauce, sometimes a splash of sake. Cooks often reach for usukuchi (薄口) soy sauce, which is lighter in colour than the regular dark kind, though actually saltier, so it seasons without darkening the broth. The aim is a soup where the seasoning barely announces itself. You should taste the dashi first, and only afterwards notice that something has brought it into focus.

That's why suimono is so often described as a test of a kitchen. A cloudy broth, a heavy hand with the salt or a tired piece of kombu shows up instantly. There's nothing to distract you.

The everyday home version is often called sumashi-jiru (すまし汁), "clear soup", and it's simpler: perhaps a few cubes of tofu, a little seaweed and some mitsuba or spring onion in a lightly seasoned clear broth. The Tokyo-style ozoni eaten at New Year is built on the same kind of broth.

Three things in one bowl

In formal Japanese cooking, a suimono is usually thought of in three parts.

• Wandane (椀種), the main ingredient: a piece of white fish such as sea bream, a soft shrimp dumpling called ebi shinjo (海老しんじょ), a clam, a block of tofu or a single fine mushroom.
• Wazuma (椀妻), the supporting garnish: a few leaves of greens, a slice of mushroom, or temari fu (手毬麩), little balls of wheat gluten coloured like the embroidered temari balls they're named after.
• Suikuchi (吸い口), the fragrant accent: a curl of yuzu peel, a leaf of kinome (木の芽, the young sprig of the sansho pepper plant) in spring, a knot of mitsuba stem or a touch of ginger.

The suikuchi is what you smell when the lid comes off, and it's the detail I find most charming. It is just a sliver, yet it changes the whole bowl.

Suimono also follows the seasons closely. A well-known example is the clam soup served for the Doll Festival, Hinamatsuri, on 3 March: the two halves of a clam shell fit only each other, so the clams carry a wish for a good marriage. In autumn, cooks may reach for matsutake mushrooms. The broth stays constant while the bowl tells you the time of year.

The bowl and the lid

Suimono is served in an owan (お椀), a wooden bowl finished with lacquer, often black outside and red inside, with a matching lid. Wood and lacquer hold heat gently, so you can cradle the bowl in your hand without burning yourself. The lid keeps the soup hot, holds in the aroma and turns the first moment into a small reveal. Some fine owan are decorated on the inside of the lid, a little private picture for the person eating.

Here's how to handle one:

1. Steady the bowl with your left hand and lift the lid with your right.
2. If the lid sticks, the heat has created a seal. Gently squeeze the sides of the bowl and it will release.
3. Hold the lid over the bowl for a second so any drops fall back in, then set it down beside the bowl with the inside facing up.
4. Sip the broth straight from the bowl and eat the solid pieces with chopsticks.
5. When you're finished, put the lid back on the bowl the way it came.

Lacquer scratches easily, so avoid flipping the lid over and stacking it on top of the bowl.

The heart of a kaiseki meal

In kaiseki (懐石), Japan's multi-course seasonal cuisine, the lidded soup course is called the wanmono (椀物), literally "bowl thing". It is often described as one of the high points of the meal: the course where a chef's dashi is most exposed and where the season is presented most clearly. Many cooks put some of their most careful work into this single bowl.

You don't need a kaiseki dinner to try suimono, though. It turns up at ryokan dinners, in set meals in place of miso soup, and at many sushi restaurants as a clear fish or clam broth. When you see it, take a moment before you sip. Lift the lid slowly, breathe in, and notice what the cook chose to place on top.

In a world of loud food, I find suimono almost radical. It asks you to slow down long enough to notice a shadow of yuzu, and it rewards you for noticing.