Slow roasting a shoulder of lamb is an excellent method of achieving a succulent meat dish that literally falls away from the bone. There are many different recipes available for lamb but the very best ones make use of easy-to-source vegetables and simple household ingredients. A shoulder of lamb to serve six people can take approximately 6 hours to cook, so allow for sufficient oven and preparation time before your guests arrive.
Preheat the oven to 182 degrees Celsius. Remove the lamb from the refrigerator approximately 1 hour before cooking begins and leave it to reach room temperature. Lightly season olive oil with sea salt and ground black pepper and rub the mixture onto the outside of the lamb until it is entirely covered. Place the lamb into the casserole dish.
Use a sharp knife to make small cuts over the lamb and fill the incisions with 6 sprigs of rosemary and the peeled cloves of one bulb of garlic. Place the remaining rosemary and garlic underneath the lamb and surround it with the onions. Add other seasonal vegetables to the casserole dish.
Place the casserole dish in the oven without the lid for 20 minutes or until the onions and any other vegetables have lightly browned. Remove the casserole dish from the oven, add the lid and put the dish back into the oven for approximately 4 hours. After 90 minutes of cooking time, remove the vegetables from the casserole dish and set them aside before returning it to the oven for the last 2-1/2 hours.
Remove the casserole dish from the oven after a total of 4 hours and sprinkle the lamb with balsamic vinegar before replacing the lid. Turn down the oven temperature to 107 degrees Celsius. Cook the lamb for 1 more hour, basting at 15-minute intervals.
Remove the casserole dish from the oven and place the lamb on a separate tray. Add the vegetables to the casserole dish and place back in the oven without the lid to complete cooking and to reduce excess fluid for 15 minutes. Remove the vegetables, baste the lamb one final time in the reduced fluids and cut into slices for serving.
Consider replacing rosemary with thyme for a different taste.