Mix the vegetables with the oil, salt and pepper, spread onto a baking tray lined with baking paper.
Roast for approx. 1 hr. in the centre of an oven preheated to 200°C. Turn the vegetables from time to time so that they brown evenly.
Place the lentils in boiling water and simmer (uncovered) for approx. 20 mins. until just soft. Drain the lentils, season with salt, allow to cool a little, mix with the roasted vegetables or serve alongside.
Combine the vinegar with all the other ingredients up to and including the yoghurt. Add the mint, season to taste. Drizzle the roasted vegetables and lentils with the dressing.