Chef's note: In Hawai‘i, making this soup is a must for New Year’s celebrations. Traditionally in Japan, the soup is served on New Year’s Day utilizing the mochi that was displayed in the house. The stickiness of mochi, pounded from individual grains of rice, represents the family staying together as one. In Hawai‘i, my family drank this soup right after the midnight fireworks celebrations as a means to start off the New Year enjoying a symbolic meal together.
In a medium size pot, combine the water and dashi powder. Add the hokkigai clams and liquid and daikon and quickly bring to a boil, then simmer for 3 minutes. Taste the broth and season with salt, if needed; divide the soup into 4 serving bowls.
Heat a medium sized non-stick pan on high heat. Add the oil and mochi; when the mochi puffs up and browns on one side, in about 1 minute, turn it over and brown the second side, then place 1 piece of cooked mochi in each bowl of soup. Divide the mizuna into 4 portions and place 1 portion into each bowl. Then, place 1 slice of kamaboko into each bowl to garnish and serve immediately.