Lightly coat a baking sheet with nonstick cooking spray. arrange eggplant slices in a colander: rinse with cold water and drain well. Pat dry with paper towels. Arrange on the same baking sheet. Sprinkle with garlic, oregano, ¼ tsp of the kosher salt, and the ¼ tsp black pepper. Drizzle with 1 tbsp of the oil. Bake, uncovered, in the 400° oven about 15 minutes or just until tender, turning once. Cool slightly and cut into 1 inch cubes.
Meanwhile, in a 2 quart square baking dish combine the remaining 1 tbsp oil, 1 tbsp of the red wine vinegar, the water, marjoram, remaining ¼ tsp kosher salt, and the ⅛ tsp black pepper. Add red onion slices turn several times to coat. Bake, covered, in the 400° oven about 20 minutes or until tender, turning the onion slices once. Cool slightly in dish on wire rack. Chop the onion, reserving any liquid in the dish.
In a large bowl combine eggplant, onion, roasted bell peppers, parsley leaves, capers, olives, lemon juice, and remaining 1 tbsp red wine vinegar.
Arrange spinach leaves on a large platter or on 8 serving plates. Top with eggplant mixture. Sprinkle with feta cheese and drizzle with reserve liquid from dish. Great served with Tandoori Chicken!
