Fill a pot with water. Add kombu, shitake, and pearled barley. Bring to a boil. Turn down flame. Add one onion, carrots, and Chinese cabbage to soup. Cover and simmer for at least an hour. Scoop out some broth and mix 1/4 cup miso into it. Return to pot and simmer on low for twenty minutes, but do not boil. Garnish with scallions and grated ginger. Serves 4.