Remove eggplant from rack and place in large bowl. Add mint, garlic, acacia flowers, 2 tablespoons vinegar and toss to coat thoroughly.
Lay eggplant slices in jar, 1 on top of other until nearly full. Place serranos intermittently between the layers. Press eggplant down into jar with fingers and add remaining vinegar. Fill jar with olive oil and cover. Place in refrigerator. The eggplant are ready to eat but will improve after aging one week. Top off with oil if the level goes below the top of the eggplant. Eat at room temperature as antipasto.