Step 1: Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper. Wash and slice the eggplants into ½-inch thick rounds or half-moons. (Optional: If salting, place slices on paper towels, sprinkle with salt, let sit 30 minutes, then pat very dry.)
Step 2: In a large bowl, toss the eggplant slices with 3 tablespoons of olive oil, dried oregano, salt, and black pepper until evenly coated.
Step 3: Arrange the eggplant in a single layer on the prepared baking sheet. Roast for 20-25 minutes, flipping halfway through, until tender and golden brown.
Step 4: While the eggplant roasts, prepare the topping. In a medium bowl, combine the crumbled feta cheese, minced garlic, chopped fresh parsley, fresh oregano, and fresh mint (if using). Drizzle with the remaining 1 tablespoon of olive oil and fresh lemon juice. Stir gently.
Step 5: Once the roasted eggplant is out of the oven, generously spoon the feta and herb mixture over the warm slices. Serve immediately, garnished with red pepper flakes if desired.