Mustard/Garlic/Herb Coating (Optional)
1 cup dijon mustard
1 head roasted garlic mashed puree (To roast a garlic head, place entire head in tin foil with a little olive oil. Bake at 375 until soft and squishy at least 30 minutes. Remove from skins and mash).
Optional: dried rosemary and thyme - 1 teaspoon each
Salt and pepper
Mix mustard, garlic puree and herbs.
Optional: Bread crumbs for crunch
Thaw the leg in the refrigerator. Depending on the size of the leg, allow 1 day for half leg to thaw and 2 days for whole leg to thaw. Let meat come to room temperature before roasting. Invest in an instant read meat thermometer in order to cook the leg properly. It is not necessary to do any special treatment to the leg but if you want, this mustard coating is nice.
Pre-heat oven to 425 degrees. If not doing mustard coating, rub olive oil over leg and sprinkle with salt and pepper. Slather mustard coating over the leg. Press bread crumbs into mustard. Place in a roasting pan. Scatter some cut-up potatoes and carrots around the roast. Roast at high heat for 15 minutes. Turn down to 350 degrees. Basting is optional - I never do.
Pull the meat out when it reaches your desired temperature. The temperature of the meat will continue to rise after it is removed from the oven. Take this into consideration. (I usually pull my roasts out when they are 10 degrees below the desired temperature.) Let leg rest for 15 minutes before carving. De-fat the pan juices and serve them alongside the lamb. They can be mixed with a little wine, salt and pepper if there isn’t much jus.
Roast Leg of Lamb Temperatures
Very rare 120 degrees
Rare 125 degrees
Medium Rare 130 degrees
Medium 140 degrees
Approximate cooking times for rare meat:
Sirloin half - 1 hour
Shank end half - 1 hour
Full leg (5 to 7 lbs) 1 1/4 to 1 1/2 hours
The temperature of the leg will continue to rise for 10 minutes. I try to err on the under-done side as the roast can always be popped back in the oven to cook a little more.
To be safe and avoid overcooking, test for doneness after 45 minutes for half leg and one hour for full leg.
How to carve: Do not cut into the center bone. Slice the meat holding your knife parallel to the bone. Use a napkin to hold onto the meat. Cut thin slices until you reach the bone. Then turn the roast over and cut the other side. Continue until all the meat is removed. Save bone for stock. Make Scotch Broth Soup with it.