Prepare the sauce In a small bowl, combine the red miso, mirin, and sugar. Mix thoroughly until smooth.
Cut the vegetables Chop the eggplant and onion into bite-sized pieces.
Sauté the vegetables Heat some oil in a frying pan and sauté the vegetables until they are nicely browned and tender.
Glaze and finish Once the vegetables are cooked through, pour in the prepared miso glaze. Stir-fry quickly over the heat to coat everything evenly, being careful not to let the miso burn. You can add the shichimi and sesame seeds at this stage if you like.
Serve Transfer to a plate and enjoy! The combination of the succulent eggplant and the rich, sweet-salty sauce is irresistible with a bowl of rice.
If you have leftovers, let them cool completely. You can wrap the mixture in a simple flour dough and pan-fry or steam it to make Oyaki—a traditional snack from Nagano prefecture. It makes for a wonderful, savoury vegetable treat!