Put the carrots and parsnips on a foil-lined baking sheet. Drizzle with 1 tablespoon of the oil, scatter over the cumin seeds, season with salt and pepper and cook in a preheated oven, 180°C (350°F), Gas Mark 4, for 20—25 minutes.
Meanwhile, make the dressing. Mix the yogurt, lemon juice, oil and ground cumin in a small bowl. Season to taste with salt and pepper.
Trim the scallops to remove the tough muscle on the outside of the white fleshy part. Heat the remaining oil in a large frying pan and fry the scallops for 2 minutes on each side until they are just cooked through. Pour over the lemon juice and transfer the scallops and cooking juices to a large salad bowl.
Add the carrots and parsnips to the bowl and mix, then transfer them to a serving dish, spoon over the yogurt dressing, garnish with parsley and serve.