Arrange the chops in a single layer in a shallow non-metallic dish. Mix the yogurt with the tomato purée, curry paste, garlic, ginger, sea salt and lemon juice, and rub into the lamb. Cover and marinate in the refrigerator for 4–5 hours or overnight.
Preheat the oven to 220°C (425°F), Gas Mark 7, and line a large roasting tin with foil. Arrange the chops in a single layer in the tin and cook in the preheated oven for 8–10 minutes, turning halfway through cooking, or until the lamb is cooked to your liking. Serve immediately with onion rings and tomato and cucumber slices.