In a small bowl, whisk the first 7 ingredients until blended; brush 2 tablespoons juice mixture over both sides of eggplant slices. Grill, covered, over medium heat until tender, 4-6 minutes on each side., Transfer eggplant to a serving plate. Stir honey and pepper flakes into remaining juice mixture; drizzle over eggplant. Sprinkle with green onion and sesame seeds.