Preheat the oven to 200°C, 400°F, Gas Mark 6.
Wrap the beetroot individually in foil and bake for around 45-60 minutes until completely tender. Meanwhile, cook the lentils in the vegetable stock and wine/water for 20 minutes or until just tender, or alternatively use ready to eat lentils. Drain and place in a bowl. Make the dressing by whisking together the shallot, vinegar, mustard, sugar, tarragon and seasoning, then whisking in the olive oil until emulsified.
Pour over the warm lentils and set aside. When the beetroot is cooked, wearing rubber gloves, remove the skins – they will just rub off - and cut into quarters. Add to the lentils and toss thoroughly to coat. Serve with slices of the goat's cheese on top.