Heat your oven to 220°C/Fan 200°C/Gas 7. Unwrap your meat. Pat it dry. Leave it to get up to room temperature.
Grate or pare the zest of your orange. Put it in a pestle and mortar or a small bowl. Set a small frying pan over a medium heat. Toast the coriander seeds till fragrant. Add to the zest with a large pinch of salt and pepper. Crush everything together. Rub all over the lamb. Pop it in a snug roasting dish.
Cut 2-3 slices from your orange (save the rest of the orange for the gravy). Tuck it under the lamb.
Roast for 25 mins till it has a golden crust. Remove from the oven. Lower the heat to 160°C/Fan 140°C/Gas 3.
Pour a mug of water into the roasting tin (not over the lamb). Cover the tin securely with foil. Roast for 2 ½ hrs.
Remove the dish from the oven. Unwrap the lamb (be careful of the steam). Transfer the meat to a cutting board. Rest for at least 30 mins before carving.
There are two options for your gravy. Our favourite is to use the juice from the orange to make up a little dressing. Whisk 4 tbsp freshly squeezed juice with 4 tbsp oil and 2 tbsp honey. Drizzle this over the carved lamb.
Or, you can warm the dish juices with a glass of white wine. Reduce by half. Swirl in the honey and a squeeze of orange juice. Tweak the seasoning to taste.
Swap the lamb mince in our Caramelised Lamb & Onion Flatbreads for shreds of leftover roast lamb,
and use any spare Fastbread Flatbreads in place of the pittas. Lovely with leftover pickle on the side.