Cut the eggplant into chunks and soak in water to remove the bitterness. You can cut the eggplant into thin slices, but larger pieces will be more filling.
Add dashi stock and eggplant (+ any vegetables) to the pot and simmer until the eggplant is soft. Add harusame bean noodles and simmer until soft.
Turn off the heat and add miso, dissolving it in broth as you add it. It's done. In the summer, it's best to heat through again after you add the miso!
The poached eggs in the soup makes it a little luxurious. After adding the miso, drop in a raw egg and simmer until it reaches the firmness you like. Kakitama would be delicious too (egg drop soup).
Story Behind this Recipe
I wanted to eat harusame bean noodle miso soup that's popular these days, but I didn't have pork! So I substituted with large pieces of soft simmered eggplant.
If you simmer the eggplant really well, the flavors will absorb well and it'll be really soft and delicious. If you go through the trouble of removing the bitterness, the flavors will really soak in. If you poach the egg, the soft-set egg yolk will mix with the harusame bean noodles. Delicious.