During the Summer Monthlong sesshin in August 2021, we had to be careful to stay healthy and well. Despite all precautions the common cold still managed to sneak it’s way in, leaving a few people sneezing and snuffling and wondering if they were O.K. (They went for a COVID test which came back negative, just in case you were wondering.)
So it seemed a good moment to make a large pot of this soup for supper. With its refreshingly hot and sour boullion and crisp beansprouts, it felt like the perfect soup to ward off a few germs.
To bring out the best flavour in a kombu stock, either soak the kombu overnight in cold water, or slowly heat it in water until it reaches boiling point, then take it out. (I learned this from Shuho-san, who once told me that over-cooked kombu tastes old and leathery, and reminded him of an old grandmas cooking. Probably how over-cooked cabbage and brussels sprouts might taste for us today!)

8 cm (4”) square of kombu seaweed (dried edible kelp)
2 medium carrots
2 medium sticks celery with leaves
100 g (1 cup) bean sprouts
2 stems green onions
1 medium clove garlic
1½ litres (6 cups) water
1 teaspoon sugar or palm sugar
Dash of cayenne pepper, to taste
75 ml (⅓ cup) soy sauce
75 ml (⅓ cup) white vinegar
1 tablespoon black sesame seeds
1 teaspoon sesame oil

Peel the carrots, and cut into thin matchstick style slices.
Separate the leaves from the celery and set aside. Cut the celery stalks into thin matchstick style slices.
Cut the green onions into very thin slices using a 45 degree angle.
Peel and thinly slice the garlic.

To make the soup bouillon, heat the water, kombu, celery leaves, garlic, and sugar in a large pot on a low flame. Gently bring to a boil then scoop out the kombu. Small dice the kombu and set aside.
Cover the bouillon and simmer the celery leaves and garlic for 10 minutes more, then scoop them out and discard.
Add the cayenne to the boullion. (The longer cayenne cooks the hotter it becomes, so be careful.) Bring back to a boil and put in the carrots and celery. Simmer for a few minutes until they are both tender. Then add the diced kombu and beansprouts.
Season with the soy sauce and vinegar, and reheat.
Serve garnished with the sesame seeds and green onions, and a drizzle of sesame oil.