Rub seaweed leaves with a damp cloth, place in 2 litres of cold water and bring to the boil slowly over a low heat (should take 10-15 minutes!). Boil slowly until the kelp is soft
Meanwhile peel the ginger and chop it finely. Remove the outer leaves from the lemon grass. Wash the lemon grass, rub dry and tap a little with the back of a knife
Take out the Tang. Add the mushrooms, ginger and lemongrass to the hot water, bring to the boil again and let it simmer for about 10 minutes on a switched-off hotplate. Pour the stock through a sieve, season with soy sauce and allow to cool
Meanwhile, wash the wing and soybeans thoroughly and drain them. Wash the corn, dab dry, cut in half first lengthwise, then crosswise. Peel and halve onions and cut into fine strips. Clean, clean and halve the mushrooms. Wash coriander, shake dry and chop finely
Heat the oil in a pot. Fry the prepared vegetables for 3-4 minutes while turning. Deglaze with 1 litre Dashi stock, bring to the boil, cover and simmer for about 5 minutes. Arrange the soup in bowls, sprinkle generously with coriander. Use the rest of the dashi stock for other purposes (e.g. miso soup)