Remove the lamb from the refrigerator 30 minutes before cooking. Preheat the oven to 180°C. To make the stuffing, heat the oil and butter in a medium frying pan, then add the onion and sauté until lightly golden and starting to soften (about 8 minutes). Set aside. Place the sundried tomatoes in a small food processor with the garlic and 3 tablespoons of the tomato oil, then process to a coarse purée. Remove to a bowl and stir in the chopped herbs, breadcrumbs and cooked onion. Set aside to cool. When the sundried tomato mixture is cooled, add the egg and mix well. It should come together easily in a ball and hold its shape. Stuff into the cavity of the meat where the bone was removed (if there is some over, roll in baking paper and tinfoil and cook alongside the meat for the last 30 minutes). Using butcher’s string, tie the leg to retain the shape while cooking. Rub lamb with a little oil (a little oil from the tomatoes, ideally) and place the meat on top of the rosemary sprigs in a shallow roasting dish to allow good air circulation. Cook for 15 minutes per 500g for medium-pink meat. Test with a skewer; the skewer should be warm when touched to your top lip. Or use a good meat thermometer and check for a temperature of 55°C–60°C. Remove lamb from the oven and let it rest, loosely covered, for about 15 minutes. Remove the string and sprinkle with flake salt. SIMON SAYS: Ask your butcher to leave the lamb shank bone in but remove the lower bone. These are sometimes sold as easy-carve legs. You can also use a butterflied leg, but you need to tie this up to encase the stuffing. If you are gluten-intolerant, try making the stuffing with half cooked brown rice and half gluten-free breadcrumbs.