Serves 6
Heat oil in a soup pot and sauté onion for 5 minutes. Add squash, celery, carrot, and water. Bring to a boil and reduce heat. Simmer for 30 minutes. In a food processor or blender, purée soup with the sesame seeds or tahini until smooth and return to the soup pot. Dilute miso in 1/2 cup of the soup. Blend in the poppy seeds and return mixture to the soup. Add mochi squares and simmer soup for another 5 minutes to cook the mochi into "dumplings". Serve immediately.