1. In a medium bowl, stir together ginger, scallions, vinegar, and sesame oil; season with salt and pepper.

2. In a 12-inch nonstick skillet with a tight-fitting lid, heat 2 tablespoons vegetable oil over medium-high. Add eggplant, and season with salt and pepper. Cover and cook, stirring occasionally, until slightly softened and lightly browned, 5 to 6 minutes. Uncover and cook, stirring occasionally, until tender and browned, 4 to 5 minutes. Transfer eggplant to a serving platter. Wipe out skillet with a paper towel.

3. Rub tuna steaks with remaining 1 tablespoon vegetable oil; season with salt and pepper. Return skillet to heat, and raise to high. Cook, turning once, until browned but still pink in the center, about 5 minutes total. Cut each tuna steak in half; divide among four plates. Spoon sauce over tuna and eggplant, and serve.