In a bowl, combine the garlic, mint, oregano and a pinch of salt. Arrange 4 eggplant slices in a layer in a small ceramic or glass dish. Sprinkle with 1 teaspoon of the herb mixture, then drizzle with 1 teaspoon of the extra-virgin olive oil. Repeat with the remaining eggplant, herbs and oil. Press a sheet of plastic directly on the eggplant; let stand at room temperature for at least 2 hours or refrigerate for up to 2 days. Bring to room temperature before serving.