Heat oven to 190C/170C fan/gas 5. Put the beetroot in a roasting tin and toss through the oil and some seasoning. Roast for 15 mins.
Toss the shallots and thyme with the beetroot, and roast for 40-45 mins until the veg are tender and starting to caramelise around the edges. Drizzle with balsamic vinegar and return to the oven for 3-5 mins until sticky and syrupy. Scatter with thyme leaves to serve.