Preheat your oven to 140 degrees.
Place the beetroots in a tray, and sprinkle with sea salt, thyme, and a splash of balsamic vinegar.
Cover the tray with tin foil and roast the beetroots for 1 hour.
Test the beetroots for doneness by inserting a knife into them. If it goes through easily, the beetroots are ready.
Remove the tray from the oven and allow the beetroots to cool.
Once cool, use gloves to peel the beetroots (they should peel easily).
Slice the beetroots thinly and arrange them in a small circle on a plate.