Heat the oven to 200C/fan 180C/gas 6. Mix the harissa paste with 1 tbsp oil and coat the wedges. Roast for 20 minutes in a shallow baking tray until golden and cooked through. Rub the lamb steaks with a little olive oil, and season. Heat a griddle pan to very hot and chargrill the steaks for 5 minutes on each side, or longer if you like it well done. Cover with foil and leave to rest. Serve alongside the wedges and salad.