Cook the beetroot in salted water for an hour or until tender when pierced the point of a knife. Leave until cool enough to handle, then remove the skin by rubbing it away with your fingers. Slice the beetroot thinly and arrange on individual plates, to cover most of the plate.
To make the dressing, put the shallots, thyme and lemon zest into a small saucepan with the cider vinegar. Bri