3 - 4teaspoontable saltdepending on the size of the leg of lamb
1teaspoonwhite pepper
½teaspoonblack pepper
1 ½teaspoondried rosemary
1 ½teaspoonthyme
2teaspoongarlic powder
1 ½teaspoondried parsley
Instructions
Pat the leg of lamb dry using a paper towel. Then place on a chopping board bottom-side up. Slice along the bone to create a cavity for the spices and to reduce the cooking time. A forequarter leg of lamb can be completely butterflied, while a hind-quarter would be more difficult to butterfly.
Liberally apply salt to the bottom and top of the lamb roast. A smaller leg of lamb can get away with 2 teaspoon of salt, but crank it up to 4 if you have a large 2kg leg of lamb.
Combine the olive oil, lemon juice and herbs, and massage into the leg of lamb. Place on a roasting rack or place the lamb on slice onions and garlic within a roasting dish. Allow the lamb to rest anywhere from 30 minutes to 1 hour. If you are resting the lamb for longer than an hour - you can leave it in the fridge.
Before you roast your leg of lamb, allow it to come to room temperature for approximately one hour.
Preheat the oven to 200°C (fan-forced). Roast the lamb for 20 minutes, then turn down the oven to 180°C and cook for a further 40 minutes, or until the internal temperature is 60 - 62° C for medium-well lamb.
BUT - if you have completely butterflied the leg of lamb, you will reduce the cooking time by half. In that case - roast for 20 minutes at 200°C for 20 minutes, and turn down the oven to 180°C and cook for a further 20 to 30 minutes.
Place the roast leg of lamb on a plate, cover with foil and allow to rest for 20 to 30 minutes before carving and serving.
All temperatures stated are for conventional ovens. Decrease the temperature by 20°C/25°F or gas mark 1 for "fan" or air-fryers.
Notes
Internal Temperature for lamb:
Rare: 46 - 48°C / 115 - 120F
Medium-rare: 48 - 52°C / 120 - 125F
Medium: 54 - 57°C / 130 - 135F
Medium-well: 60 - 62°C / 140 - 145F
Well-done: 65 - 68°C / 150 - 155F
Lamb must be brought to room temperature before cooking, which takes about an hour, this results in an evenly cooked lamb. If this step is skipped - the lamb will become overcooked on the outside by the time the inside is done.