Pour 375 ml water into a bowl and submerge 2 dried shiitake mushrooms and 5 g dried kelp (kombu) using a drop lid if you have one. Soak for at least 30 minutes to make dashi.
While you wait, dice ½ carrot and 75 g bamboo shoots. Once 30 minutes have passed, remove the rehydrated shiitake mushrooms and kombu from the dashi and cut to a similar size as the other vegetables.
Heat a pot on medium and add 1 tsp cooking oil. Once hot, add the diced vegetables and stir fry for 1 minute.
Add the 120 g boiled soybeans. (If canned, drain them first.)
Add the dashi to the pot, mix and bring to a boil.
Once boiling, reduce the heat to a simmer and add 2 tbsp Japanese soy sauce (koikuchi shoyu), 2 tbsp sake, 2 tbsp mirin, and 2 tbsp sugar. Mix and place a lid on top. Simmer for 30 minutes.
After 30 minutes, adjust the lid so that it's ajar and the excess steam can escape. Continue to simmer for 15 minutes to reduce.
Serve immediately, or for a deeper flavor, cool and reheat right before serving.