For the Beets: Wash beets well and cook in boiling salted water for 30–40 minutes or until fork tender. Transfer the cooked beets to a bowl of ice water to cool. When cool, use a towel to rub off the skin and trim the ends and set aside. Using a mandoline or sharp knife, carefully slice the beets into ⅛-thick inch rounds.
Arrange the rounds on your plates and very lightly brush with a tiny amount of the oil.
For the Salad: Wash and trim the frisee using only the tender inner leaves and pat dry.
Cook the bacon until crisp and drain on an absorbent cloth. Cut the cooked bacon into small cubes.
Wash and trim the onion and slice very thin and break apart into tiny rings.
Using a peeler, make thin slices of the dry jack cheese and break them apart into smaller pieces.
In a bowl, combine the olive oil, lemon juice and season with a little black pepper. Add the frisee, bacon and onion rings and toss to coat.
To Plate and Serve: Top the sliced beets with the salad and a few pieces of the cheese. Sprinkle with a bit of flaked salt, to taste.