Wash eggplant; cut crosswise into 16 slices, about 1/2 inch thick. Place eggplant slices on the unheated rack of a broiler pan. Broil 4 to 5 inches from heat for 4 to 5 minutes.
Meanwhile, combine the green onion, oil, vinegar, garlic, and crushed red pepper. Turn eggplant over and brush with onion mixture. Broil 4 to 5 minutes more or until eggplant is tender.
Sprinkle cheese and dried oregano (if using) over eggplant slices. Broil for 1 minute more. Sprinkle with 1 tablespoon fresh oregano (if using). If desired, garnish with fresh oregano. Serve immediately. Makes 4 servings.