Chitake mushrooms are plentiful in the woods from July, following the end of the monsoon rainy season. They have a superb taste and aroma, and make a great addition to the broth for noodle soup. In this recipe, the mushrooms are stir-fried with eggplant, then cooked in dashi stock with soy sauce and mirin as seasoning. This soup is then poured over the cooked soba noodles.