Preparation

• Heat the oven to 450°F. Cover two large rimmed baking sheets with parchment. Slice off the tops and bottoms of the beets and then slice the beets into rounds as thin as possible (1/8-inch thick is ideal). If your beets are large and tough, cut them in half first, lay them on their sides, and cut half moons instead of rounds for safer cutting. Toss the slices well with the olive oil, salt, and thyme and spread them in one layer, with a little space between each, on the two baking sheets. Roast for 20 to 25 min., swapping the pans to opposite racks halfway through. The beets will be soft and shrunken, slightly glistening on top and dark around the edges. The thinnest slices will be crisp and almost burned around the edges.
• To reheat: Spread the slices on a parchment lined baking sheet and heat in a 350°F oven for about 5 min.