This classic Japanese Clear Clam Soup (Ushiojiru) is made with kombu dashi broth and Manila clams. It‘s a light flavorful soup with only a few ingredients that takes just 15 minutes to prepare. It‘s traditionally served for Girls‘ Day (Hinamatsuri).
After you purchase your manila clams, you will need to de-grit them (mostly inactive time for 1 hour). Even though they are “ready to use,” I highly recommend doing this process. Please see my post on How to De-Grit and Clean Clams.
To Cook the Clam Soup
Gather all the ingredients.
Put 4 cups water, 1 kombu (dried kelp), and 1 lb manila clams in a saucepan and start cooking on medium heat. If you have extra time, I recommend adding kombu to the water first to let it steep for a longer time.
When small bubbles are around the edges of the pot and water is almost boiling, discard the kombu. You can also skim off the foam and scum from the surface to make a very nice clear broth. When it starts to boil, turn down the heat.
When all the clams open up, add 1 Tbsp sake. Taste the soup and add ⅛ tsp Diamond Crystal kosher salt, if needed. The clams will get chewy and hard when you cook them for a long time, so turn off the heat and serve. Pour into individual soup bowls and garnish with 2–3 sprigs mitsuba (Japanese parsley).
To Store
Keep the leftovers in an airtight container and store in the refrigerator for 2–3 days.