Prepare a medium-high (425°F to 450°F) gas or charcoal grill fire. Brush the eggplant slices with oil and season with salt and pepper.
Bring a large pot of water to a boil over high heat.
Grill the eggplant until grill marks form on one side, about 3 minutes. Flip the slices and continue to grill until the eggplant is tender, about 2 minutes more.
Cook the rice noodles according to package directions until tender.
Meanwhile, chop the eggplant into 1/2-inch pieces, and combine with the scallions in a large bowl.
In a small bowl, whisk together the mirin, soy sauce, sesame oil, and 1/4 cup warm water.
Drain the noodles, rinse under cold running water, drain again, and add to the eggplant. Toss with the sauce, mint, and cilantro. Sprinkle with the peanuts and serve.
nutrition information (per serving): Calories (kcal): 270; Fat (g): 3.5; Fat Calories (kcal): 35; Saturated Fat (g): 0.5; Protein (g): 3; Monounsaturated Fat (g): 1.5; Carbohydrates (g): 53; Polyunsaturated Fat (g): 1; Sodium (mg): 910; Cholesterol (mg): 0; Fiber (g): 3.