Grill 4 small Japanese eggplants over medium-high heat, turning, until very soft, 15 minutes. Cook 3 sliced garlic cloves in 3 tablespoons olive oil in a small skillet over medium heat, 2 to 3 minutes. Remove from the heat; add a pinch of red pepper flakes. Trim the ends off the eggplant and split open. Scrape the flesh with a fork and season with salt. Top with the garlic oil and sliced mint.