Dip the unpeeled beets in a large pot of salted boiling water and cook until tender, about 20 to 40 minutes. While still warm, remove beets from the pot with a cloth or paper towel. Then remove the stems and skin.
Slice the hot beets into rings and arrange them on a serving platter.
Before the beets cool, sprinkle them with garlic, mint, salt, and pepper. Then let them sit for 1 minute.
Sprinkle beets with vinegar and oil, and stir gently.
Serve this dish warm, at room temperature, or cooled.