Place the beets in boiling water to which 1 tablespoon of salt has been added. Return to the boil, reduce the heat, and cook gently until the beets are tender, about 30 to 40 minutes.
Remove from the heat and allow the beets to cool completely in their cooking liquid before draining. Discard the water and slip the beets out of their skins using paper towels to grasp the beets. Cut the beets into wedges.
Heat the butter in a small saucepan, add the beets and cook for several minutes before adding the mint. Shake to coat well. Add the lemon juice and the salt and pepper.