Heat your oven to 200°C/Fan 180°C/Gas 6. Fill the kettle and boil it. Scrub the carrots and halve or quarter them if they are very big. Put them in a roasting tin.
Trim the purple spouting broccoli. Trim the stalks and leaves off the kohlrabhi. Peel it. Slice it into wedges. Add them both to the tin with the carrots. Finely chop the kohlrabi stalks and leaves. Keep them for later. Fill the kettle and boil it.
Drizzle the veg with 1 tbsp olive oil. Season with a little salt and pepper. Toss the veg to coat them in the oil and seasoning. Roast for 25-30 mins till the veg are tender and a little charred.
Peel and finely chop the onion. Warm ½ tbsp oil in a pan over a low heat. Add the onion. Cover the onion with a piece of greaseproof paper. Sweat over a low heat for 8-10 mins till it's very soft but not too coloured.
Measure out 1 tsp of the cumin seeds and stir them into the onion. Add a pinch of the chilli powder (it’s spicy, so add just a little to taste). Cook for 1 min, stirring once or twice.
Drain the lentils. Rinse them. Add them to the pan 200ml hot water. Pop on the lid. Turn the heat up. Simmer for 10-15 mins till the lentils are tender and the water is absorbed. Add the kohlrabi stalks and leaves for the final 5 mins.
Rinse the quinoa under cold running water. Tip into a pan. Pour in 300ml hot water from the kettle. Cover. Bring to the boil. Turn the heat down. Simmer for 10 mins till the water is absorbed and the quinoa is tender.
Measure out another tsp of the cumin seeds. Add to a dry frying pan. Toast for 1-2 mins till they smell nutty. Sprinkle over the yogurt. Stir the lentils into the roast veg. Serve them with the quinoa and cumin yogurt.