Wash the eggplants, cut the tops off, and slice crosswise into circles about ¼ inch thick.
Use a fork to mix together the rest of the ingredients, except for the oil, in a small bowl. It should form a thin paste. Lay out the slices and use a pastry brush to coat the top of each with a thin layer of miso sauce.
Heat a generous glug of oil in large pan over high heat. When it's hot enough that a drop of water evaporates upon contact, turn the heat to medium-high and add the eggplant with the coated side down. Brush the tops of the eggplant with more sauce while the bottoms cook.
Cook until soft and slightly blackened underneath, about 5-6 minutes, checking the bottoms occasionally. Flip the eggplant and continue to cook until done on the other side, about 5 minutes more. Add more oil as needed so the eggplant doesn't dry out.
Remove the eggplant to a plate lined with paper towels. Serve hot over rice or as a side dish, or let cool and add to salad.