1The Asahi Shimbun reported on September 15th, 2012, results from a survey of the most popular fillings for miso soup. Many are as one would expect:
11. Tofu
22. Wakame
33. Abura-age (deep-fried tofu)
44. Asari (Japanese littleneck clam)
55. Shijimi (corbicula clam)
66. Nameko mushroom
77. Naganegi (Japanese leek)
88. Jagaimo (potato)
99. Tamanegi (onion)
110. Daikon
111. Nasu (eggplant)
112. Tamago (egg)
113. Fu (wheat gluten)
114. Satoimo (taro root)
115. Enokidake mushroom
116. Satsumaimo (sweet potato)
117. Myoga ginger
118. Kabocha squash
119. Mitsuba (trefoil)
220. Kyabbetsu (cabbage)
221. Kani (crab)
The popular tofu (including abura-age) and wakame will mix with a variety of other fillings. These two are also affordable and easy to work with in the kitchen so quick to get onto the table. Most likely, these are also in the house and available.
Asariand shijimi are great for making a naturally flavorful broth. Some people don’t bother eating the meat of the clams, but for some, especially children, digging out the meat is part of the fun.
Surprising fillings that did not make the top twenty, but are sometimes used, include cucumbers for a light soup and tomatoes for its sweetness and acidity. Both of these vegetables also suit a chilled miso soup. Tomatoes are famous for being paired with miso as both are rich in umami so it's no surprise to see it used.
When I am in a rush to get a bowl of soup on the table, I often use Marukome ekitai miso. It is a liquid miso that includes dashi. Simply cook the fillings in water and add some of the liquid miso.
Many responders replied that almost anything can be put into miso soup. I personally love tonjiru, a hearty miso soup with thinly sliced pork, gobo, konnyaku, potatoes, carrots. Meat in the soup makes it rich and the different vegetables and konnyaku add a texture that is missing from more simple soups.
But most of the time it's very basic vegetables from the list above. Some responders like to make miso soup filled with a variety of vegetables. My cousin is one of those people. Usually five to six vegetables. I always look forward to having miso soup at her home.
