Preheat the oven to 200°C. Place potatoes, carrots and oil in a bowl. Toss well to combine and place in a single layer on a large oven tray. Season with salt and pepper. Roast for 20 minutes. Turn potatoes and carrots and add the red onion. Roast for 15 minutes before adding pine nuts and roasting for a further 5 minutes. Set aside and keep warm.
Place lamb in a roasting dish. Combine breadcrumbs, herbs, garlic and pesto in a bowl, mix well. Press evenly over lamb racks.
Roast lamb uncovered for 10 minutes. Reduce oven temperature to 160°C and cook for a further 15-20 minutes (medium rare) or until desired doneness. Remove lamb, cover loosely, and rest for 5 minutes before cutting the racks into cutlets.
Meanwhile make the dressing by mixing lemon juice, oil and mustard. Add kale to vegetable mixture and pour over dressing. Toss gently to combine and serve with lamb.