Using mandolin on thinnest setting, thinly slice beets.

Heat large nonstick skillet over medium heat; cook bacon for 4 to 5 minutes or until crisp.  Remove with slatted spoon and set aside.  Add prunes to skillet; cook for about 2 minutes or until heated through.  Remove and reserve drippings.

Divide beets evenly among 4 plates.  Sprinkle mache over beets; crumble Feta over top.

Top salads with bacon, prunes and reserved drippings.  Drizzle with lemon juice.  Sprinkle with pepper.  Serve immediately.