Preheat the oven to Gas Mark 6, 200°C (400°F). Season the lamb with salt and pepper. Heat the oil in a pan and brown the lamb for a couple of minutes until golden. Leave to cool. Meanwhile make up the topping – combine the herbs, breadcrumbs, seasoning and butter and mix well. When the lamb has cooled, spread the mustard over the top and spoon on the herb and breadcrumb mixture. Press well onto the lamb. Place in the preheated oven and roast for 25 minutes. At this stage the lamb will be medium rare. Allow to sit in a warm place for 5-10 minutes before serving.
Delicious with roast potatoes and roast vegetables.